Physical Examination

A comprehensive examination of the knee joint is required to detect all abnormalities. This includes assessment of (1) the patellofemoral joint and extensor mechanism malalignment, which may occur if increased external tibial rotation exists owing to posterolateral ligament injury that accompanies the PCL rupture; (2) patellofemoral and tibiofemoral crepitus, indicative of articular cartilage damage; (3) gait abnormalities (excessive hyperextension or varus thrust) during walking and jogging¹⁰⁷; and (4) abnormal knee motion limits and subluxations compared with those of the contralateral knee.¹⁰⁹

Experienced clinicians are aware that patients with chronic deficiency of the PCL and posterolateral structures may develop an abnormal gait pattern characterized by excessive knee hyperextension during the stance phase.¹⁰⁷ Subjective complaints of knee instability and giving-way during routine daily activities, along with severe quadriceps atrophy, often accompany this gait abnormality. Gait analysis and retraining are required in patients who demonstrate abnormal knee hyperextension patterns before proceeding with any ligament reconstruction (see Chapter 34, Correction of Hyperextension Gait Abnormalities: Preoperative and Postoperative Techniques).¹⁰⁷ The failure to do so may lead to failure of reconstructed ligaments if the abnormal gait pattern is resumed postoperatively.

Diagnostic Clinical Tests

The medial posterior tibiofemoral step-off on the posterior drawer test is performed at 90° of flexion. The amount of posterior tibial translation will vary between knees with isolated PCL ruptures due to physiologic laxity or injury to the secondary posterolateral or medial soft tissue restraints. Posterior tibial translation progressively increases with injury to the secondary restraints. The importance of determining abnormal medial or lateral joint opening and increases in external-internal tibial rotation cannot be overemphasized, because the failure to correct these associated subluxations places PCL graft reconstructions under high in vivo forces postoperatively and risk of graft failure. The diagnostic tests and their interpretation are discussed in Chapter 20, Function of the Posterior Cruciate Ligament and Posterolateral Ligament Structures, and are shown in Table 22-1.

The exact determination of the extent of a PCL tear (partial vs. complete) can be difficult, but is essential from a therapeutic standpoint. The clinical posterior drawer test can be highly subjective, with the forces applied too variable to allow accurate determination of the status of the PCL. MRI is not always accurate in diagnosing partial PCL tears (Fig. 21-10). Frequently, this test may indicate that the ligament is completely ruptured; however, ligament continuity may still exist with some portions functioning to limit posterior tibial subluxation to only a few millimeters. Patten and associates¹¹⁷ reported only a 67% sensitivity rate of the ability of MRI to distinguish complete from partial PCL tears by identifying focal areas of ligamentous discontinuity.

FIGURE 21-10 A partial PCL rupture is shown. Even though the magnetic resonance imaging (MRI) scan suggests a complete rupture, there were remaining PCL fibers resisting posterior tibial subluxation.

The quantitative measurement of posterior tibial subluxation in knees with PCL ruptures or reconstruction is therefore important.⁶⁰ The knee arthrometer is the most frequently used device to measure posterior tibial translation after PCL injury and reconstruction. However, the knee arthrometer underestimates the true amount of posterior translation in PCL-deficient and reconstructed knees, often by several millimeters.^60,78,146 Stress radiography is the most accurate and reproducible technique currently available,^{37,43,60,78,119,132} yet only a few studies to date have used this method to document posterior tibial translation after PCL reconstruction. The authors recommend that PCL clinical investigations incorporate stress radiography to provide a more valid measure of posterior tibial translation (Fig. 21-11). To correct for tibal rotation, which can produce errors in measurement, the radiograph should be as close to a pure lateral as possible, with the two femoral condyles superimposed upon themselves. A horizontal line is placed across the medial tibal plateau and a perpendicular line determines the posterior position of each femoral condyle. A similar measurement is made for the most posterior position of the medial and lateral tibial plateau. The amount of tibial translation is the average of both of these measurements.

FIGURE 21-11 The results of lateral stress radiography on 20 patients with PCL deficiency (9 complete ruptures and 11 partial ruptures). The differences in the measurements between complete and partial PCL ruptures for the medial tibial plateau, the lateral tibial plateau, and the average of both plateaus were statistically significant (P < .01). Differences in the KT-1000 and posterior drawer measurements between complete and partial PCL ruptures were not significant. The KT measurements at 70° flexion underestimated the magnitude of posterior tibial subluxation for complete PCL ruptures.

(From Hewett, T. E.; Noyes, F. R.; Lee, M. D.: Diagnosis of complete and partial posterior cruciate ligament ruptures. Stress radiography compared with KT-1000 arthrometer and posterior drawer testing. Am J Sports Med 25:648–655, 1997.)

The integrity of the ACL is determined by Lachman and pivot shift testing. The result of the pivot shift test is recorded on a scale of 0 to 3, with a grade of 0 indicating no pivot shift; grade I, a slip or glide; grade II, a jerk with gross subluxation or clunk; and grade III, gross subluxation with impingement of the posterior aspect of the lateral side of the tibial plateau against the femoral condyle. A KT-2000 arthrometer test may be done at 20° of flexion (134 N force) to quantify total AP displacement.

Medial and lateral ligament insufficiency are determined by varus and valgus stress testing at 0° and 30° of knee flexion. The surgeon estimates the amount of joint opening (in millimeters) between the initial closed contact position of each tibiofemoral compartment, performed in a constrained manner avoiding internal or external tibial rotation, and the maximal opened position. The result is recorded according to the increase in the tibiofemoral compartment of the affected knee compared with that of the opposite normal knee.

The tibiofemoral rotation dial test at 30° and 90° is done to determine whether increases in external tibial rotation exist with posterior subluxation of the lateral tibial plateau (see Fig. 22-3).¹⁰⁹ This test is described in further detail in Table 22-1.

The presence of a varus recurvatum in both the supine and the standing positions is carefully assessed. The difference in results of these tests must be done between the injured and the contralateral normal knee owing to inherent physiologic looseness present in some individuals.

Radiographic Assessment

Radiographs taken during the initial examination include AP, lateral at 30° of knee flexion, weight-bearing posteroanterior (PA) at 45° of knee flexion, and patellofemoral axial views.

Posterior stress radiographs are done with an 89-N force applied to the proximal tibia.⁶⁰ A lateral radiograph is taken of each knee at 90° of flexion. The limb is placed in neutral rotation with the tibia unconstrained and the quadriceps relaxed. The difference in posterior tibial displacement between the reconstructed knee and the contralateral knee is recorded. More than 8 mm of increase in posterior tibial translation on stress testing indicates a complete PCL rupture.¹³²

Medial or lateral stress radiographs may be required of both knees. The patient is seated (0° knee extension) in neutral tibial rotation with the tibia unconstrained. Approximately 89 N of varus or valgus force is applied and comparison made of the millimeters of medial or lateral tibiofemoral compartment opening between knees.

Full standing radiographs of both lower extremities, from the femoral heads to the ankle joints, are done in knees in which varus lower extremity alignment is detected on clinical examination. The mechanical axis and weight-bearing line are measured to determine whether HTO is indicated before PCL reconstruction (see Chapter 31, Primary, Double, and Triple Varus Knee Syndromes: Diagnosis, Osteotomy Techniques, and Clinical Outcomes).^35,105 If the varus malalignment is not corrected, there is a risk that either a PCL or an ACL graft may fail owing to the varus thrusting forces and concurrent increased lateral joint opening producing high graft tension loads.⁹⁶

Patients complete questionnaires and are interviewed for the assessment of symptoms, functional limitations, sports and occupational activity levels, and patient perception of the overall knee condition according to the Cincinnati Knee Rating System (CKRS).⁶

Acute Ruptures of the PCL

Controversy exists in the treatment of midsubstance complete PCL ruptures, primarily owing to the lack of a scientifically-proven operative procedure that can predictably restore posterior stability and PCL function. In comparison, surgical procedures to reattach the native PCL in cases of bony avulsion injuries or peel-off injuries directly at the PCL attachment site have more predictable healing rates.^{12,73,151,152} Even in cases of PCL rupture directly at the attachment site, usually sufficient ligament substance remains for a direct repair. In select situations, an augmentation using the semitendinosus tendon may facilitate PCL repair.

Augmentation of partial PCL tears is controversial.^3,63,156 Graft reconstruction of the so-called posteromedial portion of the PCL has been described in which the “anterolateral bundle” is still intact and functional. The authors have no experience with this technique and have not performed augmentation procedures in the acute setting. Stress radiography plays an important role in determining whether an abnormal increase of 10 mm or more exists, indicating loss of PCL function. Partial ligament tears are treated conservatively with an extension brace and posterior calf pad to allow for potential PCL healing.

Critical Points PREOPERATIVE PLANNING

Acute Ruptures

• Reattach native PCL bony avulsion injuries, peel-off injuries directly at PCL attachment, predictable healing rates.

• Select knees, augmentation with semitendinosus tendon may facilitate PCL repair, add postoperative protection.

• Partial or acute isolated PCL tears

Immobilize 4 wk in full knee extension brace or bivalved cylinder cast.

Lateral radiograph verifies no posterior tibial subluxation.

2 wk: 0°–90° of motion maintaining anterior tibial translation load. Patient sleeps in brace, no unsupervised knee motion.

4 wk: active quadriceps extension out of brace, 50% weight-bearing, crutch support, maintain brace protection.

5–6 wk: wean from the brace and crutch support, rehabilitation (see Chapter 23, Rehabilitation of Posterior Cruciate Ligament and Posterolateral Reconstructive Procedures).

• Acute PCL injuries with associated rupture to medial or posterolateral structures: delay reconstruction until neurovascular status and other injuries are resolved and major knee ligament surgery can be safely performed.

• Associated posterolateral ruptures: acute anatomic repair required within 14 days before scarring occurs.

• PCL graft reconstruction in select athletes before secondary restraints stretch out with subsequent reinjury, arthritis.

Chronic Injuries

• Assess patient symptoms, goals, athletic desires: may indicate PCL reconstruction required.

• Varus malalignment: osteotomy before PCL reconstruction.

• PCL plus medial or posterolateral ligament injury, complex instability pattern, usually surgical candidate.

• Severe arthrosis: not expected to benefit from PCL reconstruction.

• Nonoperative approach chronic PCL tears: warn that return to athletics carries uncertain prognosis, joint arthrosis may eventually ensue.

• Consider bone scan, MRI cartilage sequences.

• Initiate rehabilitation, patient education, avoid high knee flexion activities.

MRI, magnetic resonance imaging; PCL, posterior cruciate ligament.

The treatment rationale for patients with acute PCL ruptures is shown in Figure 21-12. The algorithm is divided into three major sections based on the PCL tear (partial, complete, or combined with other ligament ruptures). The 10-mm division is somewhat arbitrary. As discussed, stress radiography is helpful in determining the exact increase in posterior tibial translation. The rules to treat partial or acute isolated PCL tears are

FIGURE 21-12 Treatment algorithm for acute PCL ruptures.

In the authors’ experience, 4 weeks of protection to allow initial healing of a complete PCL rupture will frequently restore partial PCL function, with less than 10 mm residual posterior tibial subluxation. The initial PCL healing process involves a low tensile strength and an additional 4 to 6 weeks of protection is recommended, including avoiding athletics, running, walking on downhill grades, walking down stairs, or other high knee flexion activities that load the PCL. Even in knees with a complete PCL tear and more than 10 mm of increased posterior tibial displacement, healing of the disrupted PCL fibers may still occur, although a residual posterior tibial subluxation of a few millimeters (with a hard endpoint) will remain. These knees in which partial PCL function has been restored should be followed and repeat stress radiographs obtained at 6 months and over the next few years to determine PCL function. These partial PCL tears seldom require reconstruction. However, Shelbourne and associates^136,137 described that one third or more of patients in this group have abnormal knee scores and pain with athletic activities owing usually to concomitant articular cartilage damage. A repeat MRI with fast-spin-echo cartilage sequences¹²² helps determine the integrity of the articular cartilage and provides important information for counseling the patient on athletic activities to decrease the risk of future joint arthritis.

In cases of complete isolated midsubstance PCL ruptures that have more than 10 mm of increased posterior tibial displacement in which the patient is seen late after the injury and the previously discussed program cannot be instituted, one treatment approach in athletes and those in strenuous high-risk occupations is PCL graft reconstruction before the secondary restraints stretch out with subsequent reinjury. The authors believe that, in athletic individuals, PCL reconstructive procedures have advanced to the point at which more predictable results can be expected to restore sufficient PCL function to prevent gross posterior tibial subluxation. Studies have demonstrated, at least in the short term, that the majority of patients with acute PCL ruptures treated with reconstruction are able to return to various levels of sports activities.⁹⁵ Additional factors to be weighed in the decision to perform early surgery on an isolated PCL rupture (with > 10 mm posterior displacement, 90° flexion) include athletic goals, body weight, medial meniscus or tibiofemoral joint damage, patellofemoral joint damage, and varus malalignment; these factors add to the effects of the residual posterior subluxation in increasing knee joint loads and subsequent joint deterioration. Future long-term clinical studies will confirm the importance of these factors in the operative decision of early restoration of PCL function in active younger individuals who subject their knee to high forces in sports or work activities. Sedentary patients with a complete PCL rupture and more than 10 mm of posterior translation (90° flexion) are not considered surgical candidates; however, they are followed as previously described.

Patients with a PCL disruption and other ligament injuries have an obvious posterior tibial dropback without a firm endpoint on posterior drawer testing, and 10 mm or more of posterior tibial subluxation. In almost all of these knees, some increase in medial or lateral joint opening or external tibial rotation can be detected, although the findings may be subtle. There may be physiologic laxity of other ligament structures without a true injury (see Chapter 3, The Scientific Basis for Examination and Classification of Knee Ligament Injuries) that allows for the gross posterior tibial subluxation.

In knees that present with acute disruption of the PCL and medial or posterolateral structures, reconstruction should be delayed until the neurovascular status and other injuries are resolved and major knee ligament surgery can be safely performed. In knees that have associated posterolateral ruptures, acute anatomic repair is required within 14 days before scarring occurs and the ability to anatomically restore these structures is lost (see Chapter 22, Posterolateral Ligament Injuries: Diagnosis, Operative Techniques, and Clinical Outcomes). A similar situation exists for the medial ligament structures; however, these tissues are easier to reconstruct later if surgery cannot be performed in the ideal time period for anatomic repair. There may exist a displaced meniscus tear requiring early treatment. As a word of caution, a displaced meniscus should be reduced into the tibiofemoral joint by 3 weeks to prevent meniscus shortening and scarring that compromises a future repair and results in loss of meniscus function. Even in knees that have marked soft tissue swelling and edema, and in which major ligament reconstruction is contraindicated, a meniscus repair procedure using all-inside techniques can be performed to reduce the meniscus to a normal tibiofemoral position. The mistake is to wait until 6 weeks or later, expecting that the meniscus repair can be performed at that time.

Too frequently, major ligament surgery in dislocated knees performed under acute conditions results in joint arthrofibrosis, compromising the result. Patients should be carefully selected for acute multiligament repairs, realizing that there are proven techniques for reconstruction of the ruptured ligaments performed later under more ideal conditions. When surgery is performed on acute combined PCL and posterolateral ruptures, the procedure includes the use of appropriate grafts to restore lateral stability and allow an early protected range of knee motion program, described in Chapter 22, Posterolateral Ligament Injuries: Diagnosis, Operative Techniques, and Clinical Outcomes. The majority of acute knee dislocations should be treated in a staged approach by first treating the acute injury and then determining whether a ligament reconstruction should be performed either within the 10- to 14-day envelope or delayed. When early surgery is not advisable, the knee is protected for the first 4 weeks to prevent posterior tibial subluxation, as already described for acute isolated PCL ruptures. A lateral radiograph is obtained with the knee placed in a posterior plaster shell and a soft bolster positioned beneath the calf to prevent posterior tibial subluxation. The capsular tissues heal in 7 to 10 days to provide enough stability to prevent recurrence of dislocation.

If a nonoperative approach is selected with associated MCL and posteromedial capsular disruptions, the same program is followed with the lower limb placed in a cylinder cast to allow “stick-down” of the medial soft tissues. Plaster immobilization is required because a soft hinged brace, even if maintained at 0° of extension, does not provide sufficient protection to maintain medial joint line closure to allow the disrupted medial tissues to heal. At 7 to 10 days, the cylinder cast is split into an anterior and a posterior shell and the therapist assists the patient with range of motion from 0 to 90° in a figure-four position with the hip joint externally rotated to protect the healing medial tissues. This program of “aggressive” nonoperative treatment of associated medial ligament injuries is described in further detail in Chapter 25, Rehabilitation of Medial Ligament Injuries.

Chronic Ruptures of the PCL

The algorithm for the treatment of chronic PCL ruptures is shown in Figure 21-13. The symptoms and clinical examination determine the functional limitations, particularly the component of symptoms due to medial tibiofemoral or patellofemoral arthritis because these problems are likely to persist after surgical stabilization. Knees with chronic PCL ruptures are arbitrarily divided into three categories; those with varus osseous malalignment (and, rarely, valgus malalignment) in which an osteotomy must be considered, those with an isolated PCL rupture in which reconstruction may or may not be necessary, and those with significant combined ligament injuries that require reconstruction.

FIGURE 21-13 Treatment algorithm for chronic PCL ruptures. *Arthrosis rating: standing 45° tibiofemoral and patellofemoral views or magnetic resonance imaging special cartilage sequences.

Patients are entered into a formal rehabilitation program to correct muscular weakness and gait-related problems (hyperextension) when required. The amount of joint arthritis must be determined with accuracy. Radiographs (merchant, standing PA at 45°) and MRI articular cartilage fast-spin-echo sequences provide valuable information.

In knees with no or only mild articular cartilage damage, an assessment of the patient’s goals and athletic desires may indicate the need to proceed with PCL reconstruction. Combined ligament ruptures that produce complex instability patterns require careful clinical assessment to detect all of the joint subluxations and ligament deficiencies present.

Knees that have advanced arthritis are not expected to benefit from ligament reconstruction. In these knees, areas of exposed bone are frequently encountered in the medial tibiofemoral compartment, along with diffuse cartilage fragmentation in the patellofemoral joint. In these individuals, even mildly strenuous exercises aggravate the joint arthritis symptoms and cannot be performed. The patients’ initial experience with rehabilitation, and the inability to perform the required rehabilitation exercises, provides important information regarding the amount of joint arthritis present and joint symptoms that are likely permanent.

If a nonoperative approach is elected, the clinician should warn the patient that the return to athletic activities may carry an uncertain prognosis, and that although sports may be resumed in the short term, some form of joint arthritis will eventually ensue. It is therefore important to follow the patient at regular intervals. A bone scan may be used to provide some indication of abnormal blood flow dynamics; however, it is the authors’ experience that the onset of pain and swelling usually indicates more advanced joint damage and a poor prognosis after PCL reconstruction. An MRI with fast-spin-echo sequences¹²² provides a baseline for repeated studies at 1- to 2-year intervals. The nonoperative treatment protocol of chronic PCL injuries involves educating the patient to avoid activities such as lunges and other high knee flexion activities that increase posterior tibial subluxation.

Selection of Tibial Attachment Techniques: Arthroscopic All-Inside versus Open Tibial Inlay Approach

The arthroscopic-assisted placement of the tibial tunnel avoids the added operative time and complexity of the posteromedial tibial inlay approach. The surgeon must have extensive arthroscopic experience to safely perform this procedure in order to identify the PCL posterior tibial attachment site, avoid penetration into the posterior capsule and subsequent damage to the neurovascular structures, and place the tibial tunnel into the anatomic PCL tibial footprint. Specially designed instruments, drill guides with safety stops for guide pins, and drills are available to lessen the serious risk of inadvertent penetration of instruments posteriorly and damage to neurovascular structures.

The all-inside arthroscopic technique is particularly advantageous in knees with multiple ligament ruptures that require repair and reconstruction. In these knees, high-strength grafts are used to reconstruct the PCL and ACL, which are appropriately tensioned and fixed to reduce the tibiofemoral joint to its normal AP position. Medial or lateral operative approaches are used for concurrent medial and posterolateral ligament and soft tissue repairs or reconstructions. A combined ACL/PCL/MCL injury involves an all-arthroscopic approach for the ACL and PCL, followed by a limited medial dissection for repair of the medial tissues and meniscus attachments.

Combined ligament injuries, particularly those involving medial ligament and muscle tissues, have a high rate of postoperative motion problems and arthrofibrosis. In these knees, an open posterior tibial inlay procedure and popliteal dissection may be avoided by using the all-inside arthroscopic approach. One exception is a PCL avulsion fracture from the tibial attachment. Another exception is a PCL revision knee in which a prior tibial tunnel was used and a tibial inlay graft is required to bypass this tunnel. In these cases, loss of the normal bony architecture about the posterior tibial PCL attachment may exist and a tibial inlay bone graft is required. In other PCL revision cases that have enlarged tibial tunnels, a staged bone graft procedure may be indicated with the preference to use autogenous bone (limited iliac crest graft; see Chapter 31, Primary, Double, and Triple Varus Knee Syndromes: Diagnosis, Osteotomy Techniques, and Clinical Outcomes), supplemented with allograft bone when required. The bone grafting of the enlarged or misplaced tibial tunnel is first done from an anterior approach. After the tunnel has healed, either a tibial tunnel or a tibial inlay PCL reconstruction may be performed as indicated.

The posteromedial tibial inlay technique places a tibial inlay graft securely into the posterior PCL tibial attachment site. This approach is often selected when only the PCL requires reconstruction. The tibial inlay graft provides ideal graft fixation and early healing. A two-strand autogenous QT-PB graft with two femoral tunnels is described and results have been published.^92,93

The all-inside technique has the theoretical disadvantage of the collagenous portion of the graft abrading against the angulated posterior tibial tunnel. There are operative techniques designed to diminish this problem. These include creating a more oblique tibial tunnel drilled through the anterolateral tibia and carefully chamfering the tunnel exit. Collagen grafts with a large cross-sectional area and diameter are favored over those with a smaller area and diameter in which any abrasion compromises graft strength. To decrease soft tissue graft abrasion at the tibial tunnel, the bone portion of the graft is placed in a tibial tunnel directly adjacent to the tunnel exit. The intent is to match the beneficial effect of the tibial inlay procedure allowing prompt osseous healing.

Biomechanical studies of PCL reconstructions also show the potential for graft abrasion and failure at the femoral attachment.¹³⁴ Operative techniques to protect against graft failure and abrasion are necessary at both tibial and femoral attachment sites.

Selection of PCL Femoral Attachment Techniques: Two-Tunnel versus Single-Tunnel Options

It is not difficult from a technical standpoint to use two well-placed femoral tunnels within the PCL femoral footprint from outside-in, and this is the most ideal technique to master. When the tibia inlay or tibial tunnel bone plug two-strand graft procedure is selected, two femoral tunnels are created using the outside-in technique with a limited anteromedial subvastus approach, described later. This allows graft tensioning, a long femoral tunnel for graft incorporation, and graft fixation with a suture post. This is the author’s preferred technique with either an autograft or an allograft (see Table 21-5).

The 4 o’clock posterior PCL graft strand is shorter by at least 15 mm than the 1 o’clock anterior graft strand. The outside-in tunnel approach allows accurate tensioning, fixation, and visualization of the graft length change during knee flexion. This allows the surgeon to determine the ideal knee flexion position for graft fixation.

In the alternative technique in which the bone portion of the graft is placed at the femoral site, a rectangular femoral slot technique is preferred. The bone plug is fixated with an inside-out arthroscopic technique. The rectangular slot technique places the bone within the PCL femoral footprint, which is more ideal than a single large-diameter tunnel, although either technique may be used. One or two tibial tunnels are used for the collagenous portion of the graft, described later. In a PCL revision procedure, a misplaced femoral tunnel may exist in which the bone portion of the graft is preferred over one or two soft tissue femoral graft tunnels.

A single femoral tunnel drilled from an inside-out anterolateral portal is more difficult because of the narrow intercondylar notch, the proximity of the lateral femoral condyle, the placement of the tunnel within the PCL footprint, and the need to avoid too proximal (deep) placement of the tunnel with portions of the graft outside of the PCL footprint. For these reasons, the outside-in drilling approach for a single large-diameter femoral graft tunnel is recommended for surgeons using this technique.

The options for femoral and tibial fixation for a bone–patellar tendon–bone (B-PT-B) graft are shown in Tables 21-6 and 21-7, respectively.¹⁴ Techniques are available for inside-out drilling of tunnels and fixation of soft tissue grafts at the femoral attachment site using interference screws (similar to that performed in ACL reconstructions).⁶¹ However, these techniques result in lower attachment strength. The outside-in approach allows graft sutures and a suture post to be incorporated (Tables 21-8 and 21-9). PCL reconstructions are under high in vivo loads (see Chapter 20, Function of the Posterior Cruciate Ligament and Posterolateral Ligament Structures) and it is advantageous to select graft fixation methods that provide for maximum tensile strength of the graft construct.^17,82,142

Selection of Single-Strand versus Two-Strand PCL Graft Constructs

The advantages and disadvantages of one- and two-strand PCL graft techniques are summarized in Table 21-10. The goal of adding a second strand is to place additional collagenous tissue within the PCL footprint to increase the cross-sectional area of the graft and more closely replicate the native PCL attachment. This theoretical advantage is sometimes referred to as the mass action effect of adding additional collagen within the PCL footprint. The improved stability and clinical success of a two-strand graft construct over those of a single-strand graft have not been proved from a clinical standpoint. Some clinical studies show that a single graft strand obtains results similar to those of a two-strand procedure.

TABLE 21-10 Basis for the Selection of One- Versus Two-Strand Posterior Cruciate Ligament Reconstruction

+ Denotes relative advantage; – denotes relative disadvantage.

* Proven by objective measurements, including stress radiography at 90° of knee flexion.

The incorporation of a second graft strand has the theoretical advantage of providing additional collagen tissue for load-sharing, which decreases stress in the collagen fibers, increases graft strength, and reduces cyclic fatigue of the graft construct.^134,159 The two graft strands are tensioned at surgery to share loads, which decreases the loads compared with those of a single PCL graft construct. This has been shown in a majority, but not all,⁸¹ biomechanical studies that compared single- and two-strand graft constructs. Studies report that the two graft strands placed in the distal two thirds of the PCL femoral footprint will function to resist posterior tibial translation with increasing knee flexion (see Chapter 20, Function of the Posterior Cruciate Ligament and Posterolateral Ligament Structures). Alternatively, when two graft strands are placed in a proximal and distal (deep and shallow) portion of the PCL footprint, graft loading is in a reciprocal manner and the graft strands are under higher loads, which is less ideal. As previously noted, the length and tension changes in grafts is governed for the most part by the femoral attachment, and any graft fibers in the distal two thirds are subjected to increasing tension and elongation with knee flexion.^53,140

Critical Points SELECTION OF SINGLE-STRAND VERSUS TWO-STRAND POSTERIOR CRUCIATE LIGAMENT GRAFT CONSTRUCTS

• Goal of second strand: place additional collagenous tissue within PCL footprint, increase cross-sectional area of graft, more closely replicate native PCL attachment. Decreases stress in collagen fibers, increases graft strength, reduces cyclic fatigue of graft construct.

• Second strand placed further posterior in the femoral footprint. Graft placed in distal two thirds of footprint functions to resist posterior tibial translation with increasing knee flexion.

• Biomechanical studies justify two-strand reconstruction restores posterior tibial translation to normal values.

• Clinical studies report residual posterior tibial drop-back at high knee flexion angles in majority of single-strand PCL reconstructions.

• Two-strand graft constructs

QT-PB, bone plug placed femoral or tibial attachment. Tendon split into two strands, tensioned separately.

Two separate grafts placed into two separate femoral and tibial tunnels.

• Controversy exists between well-placed single-strand and two-strand grafts owing to inadequate clinical data.

• Authors’ opinion: sound theoretical reasons exist to warrant two-strand PCL reconstruction when clinically feasible.

PCL, posterior cruciate ligament; QT-PB, quadriceps tendon-patellar bone.

In Chapter 20, Function of the Posterior Cruciate Ligament and Posterolateral Ligament Structures, the function of PCL grafts is described in detail. The usual description of a posteromedial bundle that resists tension with knee extension and an anterolateral bundle that resists tension with knee flexion represents an oversimplification and an inaccurate representation of PCL fiber behaviors. In this chapter, the rule of thirds (see Fig. 21-8) is used to describe PCL fiber and graft function.

In a cadaveric study, Bergfeld and coworkers¹⁰ reported that both single- and two-strand PCL reconstruction restored translation after PCL sectioning, and suggested that the additional strand may have no benefit. The same-diameter Achilles graft was used so that additional graft material was not added by the second strand. However, the graft forces were not measured and it was not determined whether the second strand resulted in a decrease in graft tensile forces. Studies show that a single graft will restore posterior translation limits to normal after PCL sectioning^11,77,135; however, commonly at the expense of high graft tensile forces. Therefore, the theoretical advantage of the second graft strand is to lower the high graft forces placed on a single graft strand and decrease graft failure from cyclic loading (see Chapter 20, Function of the Posterior Cruciate Ligament and Posterolateral Ligament Structures).

In a cadaveric study, Harner and associates⁵⁶ reported that a single-strand PCL reconstruction did not restore normal posterior tibial translation or joint kinematics. These investigators found that a two-strand PCL reconstruction did restore posterior tibial translation to normal values. The difference found between the single- and the two-strand constructs may have been due to inadequate tensioning of the grafts. The single-strand grafts were tensioned to 88 N at 90° of knee flexion. The tension required to restore posterior tibial translation was not measured and would have required higher graft loads. The added 67-N tensioning of the second posterolateral graft strand provided the additional resistance to restore the tibia to a normal posterior position. Thus, the authors did not truly compare the single- and two-strand PCL graft constructs under the same loading conditions.

A justification to add a second PCL graft stand is the frequent notation in clinical studies that at high knee flexion angles, there is a residual posterior tibial drop-back in the majority of PCL reconstructions.⁹⁵ There is no question that current PCL surgical procedures are not uniformly accomplishing a functional restoration of normal joint kinematics and stability postoperatively. This is further discussed in detail in the “Authors’ Clinical Studies” section of this chapter. The concern is that residual posterior tibial displacement decreases the ability of the medial meniscus, and perhaps the lateral meniscus as well, to function,¹¹⁸ thereby increasing tibiofemoral contact pressures.^72,141 Increases in patellofemoral contact pressures have also been reported.⁵⁰

There are two types of two-strand PCL graft constructs. One example is the QT-PB graft with the bone plug placed at the femoral or tibial attachment and the tendon split into two strands, which are tensioned separately and ideally placed in two separate tunnels. The other type of PCL two-strand graft construct consists of two separate grafts placed into two separate femoral and tibial tunnels. For purposes of load-sharing between graft strands with knee flexion, it is not known whether there is any difference between a single bone attachment and two separate bone attachments. In the authors’ opinion, there is no functional difference between these two graft constructs that can be measured.

A technique is available to pass two bone plugs through a single tibial tunnel in which one bone plug is sutured to the tendon just proximal to the other bone plug, placing two bone plugs in series. Sutures are placed into each bone plug, and an interference screw is added in the tibial tunnel. It is difficult to pass the double graft construct into the tibial bone tunnel, which is drilled 1 to 2 mm larger in diameter. This technique is not recommended; a larger-diameter single tibial tunnel with an appropriate-sized single bone plug is preferred.

When an AT-B allograft is selected, it is important that the graft be inspected to discard those that have a narrow tendon section just adjacent to the bone attachment. A QT-PB allograft is a more suitable PCL substitute owing to the larger cross-sectional area of the tendon; however, this graft is more difficult to obtain from tissue banks.

Multicenter randomized, controlled trials of one- and two-strand PCL reconstructions are required in the future to provide a more scientific basis for selection of one type of graft procedure over another. The surgeon is currently faced with small clinical trials with level 4 evidence, described later this chapter. For this reason, more than one PCL technique is described with recommendations regarding the technical issues to maximize the clinical result. The authors’ preferred PCL graft procedures are provided along with the justification and rationale for these selections. In addition, it is necessary to use a case-by-case basis for selecting the appropriate surgical procedure in multiligament knee injuries.

In summary, there appear to be sound theoretical reasons to warrant a two-strand PCL reconstruction when clinically feasible. These conditions include isolated PCL reconstructions when the added time required to perform a two-strand PCL graft does not represent a contraindication in terms of operative time and complexity. In multiligament reconstructions, the primary goal is to repair and reconstruct all ruptured ligaments. Adding a second femoral tunnel, and tensioning and securing two graft strands, may be time-consuming in an already complex surgical reconstruction. Therefore, the surgeon should be prepared, based on the operative findings, to modify the preoperative plan when required. In certain multiligament-injured knees, a single-strand PCL graft construct may offer a reasonable opportunity to restore functional stability (Fig. 21-14).⁸¹ Given the complex PCL fiber microgeometry, either a single- or a two-strand graft construct still represents an imperfect substitution, providing only a check-rein effect in controlling joint motions and subluxations.

FIGURE 21-14 Posterior stress radiograph of a patient 2 years after a single-strand PCL quadriceps tendon–patellar bone (QT-PB) autograft shows only 2 mm of increased posterior tibial translation. The patient had sustained a knee dislocation and also underwent an anterior cruciate ligament (ACL) bone–patellar tendon–bone (B-PT-B) allograft reconstruction, and an anatomic posterolateral reconstruction with a fibular collateral ligament (FCL) B-PT-B allograft.

Selection and Preparation of PCL Grafts for Tibial Inlay and All-Inside Techniques

The mechanical properties of grafts commonly used to reconstruct the PCL are shown in Table 21-11. The goal of PCL surgery is to select a graft that matches the structural properties of the PCL as closely as possible. The problem is that the PCL is a highly complex ligament composed of fibers of different lengths that are brought into the loading configuration based on the knee flexion and tibial rotation positions. The data show initial graft mechanical properties that are expected to decline after graft implantation and in vivo remodeling. It is thus not possible to match the complex PCL microgeometry with any tendon substitute.

The cadaver age in the investigation by Race and Amis¹²⁴ ranges from 53 to 98 years. Previous investigations by the senior author and Grood¹⁰⁸ and others¹⁶¹ documented significant reductions in strength and stiffness properties of ligament units with advancing age. For instance, one study documented that whereas ultimate failure of ACL-bone grafts occurred at a mean of 1730 N in young cadavers (aged 16–26 yr), this value decreased to a mean of 734 N in older cadavers (aged 48–86 yr).¹⁰⁸ Race and Amis¹²⁴ estimated that a PCL reconstruction should be designed to match a native PCL with a strength of 4000 N, and not the approximate 2000 N shown in Table 21-11 (for both bundles combined).

In a study of 14 cadaveric PCL specimens (mean age 52 yr; range, 30–83 yr), Harner and associates⁵⁸ reported a mean ultimate load to failure of the anterolateral PCL bundle of approximately 1200 N and of the posteromedial bundle of 400 N. This provides an ultimate failure load of the entire PCL in the 1600- to 1700-N range, well below that expected, which is most likely due to the advanced age of the cadaver specimens.

In a similar manner, large variations may exist in reported strength and stiffness data based on the testing apparatus and manner in which soft tissues are grasped without inducing premature failure. For example, the strength of the quadriceps tendon construct shown in Table 21-11 is 2353 N; however, the mean cross-sectional area is 65 mm². Different methods that affect these values are used to measure cross-sectional area. The senior author and coworkers¹⁰⁶ previously described a method that induced a low level of compressive force to compress the soft tissues into a block of defined dimensions that provided an accurate cross-sectional measurement. The data shown in Table 21-11 are derived from investigations that used different area measurement systems, making comparisons difficult.

The principles for the selection of all-inside and tibial inlay grafts are summarized in Tables 21-12 and 21-13.

TABLE 21-12 All-Inside Posterior Cruciate Ligament Graft Options

AT-B, Achilles tendon–bone; B-PT-B; bone–patellar tendon–bone; PCL, posterior cruciate ligament; QT-PB, quadriceps tendon–patellar bone.

TABLE 21-13 Tibial Inlay Posterior Cruciate Ligament Graft Options

AT-B, Achilles tendon–bone; B-PT-B; bone–patellar tendon–bone; PCL, posterior cruciate ligament; QT-PB, quadriceps tendon–patellar bone.

* Single tibial inlay bone block, two separate femoral tunnels at 1 o’clock and 4 o’clock to maintain bone bridge between tunnels, preferred over single tunnel.

† Single tibial inlay bone block, one femoral tunnel 1 o’clock position.

‡ Preference for two-strand graft when added complexity of the tibial inlay approach is used, single strand provided for completeness.

Preparation of QT-PB Autograft

A tourniquet is inflated to 275 mm of pressure. This is usually the only time the tourniquet is used in the reconstructive procedure, except when the open tibial inlay approach is selected. An incision is made just medial to the superior pole of the patella and extended proximally 5 to 6 cm (Fig. 21-15). The incision also allows access to the anteromedial aspect of the medial femoral condyle and vastus medialis obliquus (VMO) for subvastus placement of the femoral tunnels. A cosmetic approach is used with subcutaneous dissection performed circumferentially about the incision to allow the skin to be mobilized superiorly and inferiorly for the graft harvest. With this technique, no incision is required over the patella.

FIGURE 21-15 QT-PB autograft harvest. A, Medial incision. B, The quadriceps tendon is carefully marked to remove only 30% of its width and not extend to the musculotendinosus junction. C, A central 11- to 12-mm-wide full-thickness quadriceps tendon graft is harvested. The defect is later closed to maintain arthroscopic joint distention. D, Illustration of graft harvest. E, Two-strand 8-mm tendon graft with patellar bone is prepared.

The graft length and thickness are marked on the tendon and the proximal musculotendinous junction is avoided, which would weaken the extensor mechanism. The quadriceps tendon appears more narrow proximally, and it is important not to remove more than one third of the tendon. In some patients, there is a shortened quadriceps tendon that is not suitable for harvest, and the patient is advised preoperatively and provides consent for either an autograft or an allograft approach. The quadriceps tendon must be a minimum of 70 mm, not counting the patellar bone plug, to be a suitable graft. The full-thickness quadriceps tendon graft is taken from the central tendon and is 10 to 11 mm in width and thickness. The quadriceps tendon consists of three layers: rectus tendon, VMO–vastus lateralis obliquus (VLO) combined tendon, and the vastus intermedius tendon. A meticulous technique is followed to incise all three layers in a perpendicular fashion with a new blade. The tendency is to not harvest the deep layer or to allow the blade to assume an oblique plane rather than a perpendicular plane. A curved instrument is placed behind the three tendon layers at the proximal aspect of the tendon harvest site to protect the underlying joint synovium. If the synovium is entered, it is closed along with the remaining quadriceps tendon closure to maintain joint distention for the arthroscopic procedure.

An Ellis clamp is placed about the three ends of the tendon to maintain tension. Care is taken at the quadriceps tendon attachment to the patella, because the tendon attachment is located at the proximal and anterior third of the proximal patella. A plane is established at this point just behind the quadriceps tendon attachment to preserve the posterior underlying synovial attachment and adjacent soft tissues. These tissues provide a superior buttress for the bone grafting of the patella to close the defect and secure the bone graft.

The patella bone block matches the quadriceps width, which is usually 10 to 11 mm wide. The bone block length is 22 to 24 mm and the depth is 8 to 10 mm. A thin powered saw blade is marked with a Steri-Strip to a depth of 10 mm to prevent a deep penetration. The saw is kept perpendicular to the patella for all cuts. After the anterior bone cuts are made, the quadriceps tendon is lifted superiorly at its attachment site. The inferior portion of the bone block is cut in a perpendicular manner beneath the quadriceps tendon attachment to a depth of 8 to 10 mm. This allows the bone block to be gently removed for graft preparation. The tourniquet is deflated and hemostasis obtained.

The graft is prepared based on whether the one-strand or two-strand technique is selected. The tendon graft strands are sutured in a meticulous manner using three nonabsorbable 2-0 sutures with two or three whipstitches beginning and exiting at the end of the graft strand. In the tibial inlay technique with one graft strand and a single femoral tunnel, all three tendon layers are sutured together for tendon passage into the femoral tunnel. The graft diameter is sized for the appropriate tunnel to be drilled. In the tibial inlay or posterior tibial bone plug technique with two femoral tunnels (authors’ preference), the tendon is split in a longitudinal manner and two graft strands are fashioned. A blood-soaked sponge from the wound site is wrapped around the graft to provide protection, keep the tissues moist, and potentially maintain cell viability.

In the optional all-inside technique with the patellar bone block placed into the PCL femoral attachment, either a one-strand or a two-strand technique may be selected for the graft strands placed though the tibial tunnel. When a single tibial tunnel is selected, there is still the advantage of tensioning the two graft strands separately.

The quadriceps tendon and synovium are closed to provide a fluid tight closure allowing joint distention. The quadriceps tendon defect is loosely closed with nonabsorbable 0 sutures. The tendon is closed in a Z-plasty manner, in which portions of the quadriceps tendon layers are brought together to avoid the use of circumferential tight sutures placed through all three tendon layers to decrease medial-to-lateral tension in the extensor mechanism.

The patellar bone defect is later bone-grafted in a meticulous manner with bone obtained with a coring reamer during preparation of the femoral graft tunnels. It is important to obtain a bone graft that completely fills the defect, because bone shavings from the tunnel preparations are insufficient. Postoperatively, a bone defect that was meticulously grafted heals without a palpable patella defect and decreases the incidence of graft harvest site pain.

Preparation of AT-B Allograft

The preparation of an AT-B allograft is performed in a manner similar to that of the QT-PB autograft, already described. The only difference is that it is necessary to tube each portion of the single- or double-strand graft because the tendon has a wide proximal fan shape. Care is taken when performing the incision of the tendon into two strands close to the bone attachment, because the tendon narrows in this area. For these reasons, the AT-B graft is generally used for single tibial and femoral tunnel applications, with the bone plug placed in a posterior tibial tunnel location. In the optional technique described, the bone plug is placed into a rectangular femoral site for all-inside placement, or a 10- to 11-mm-diameter graft for a single femoral tunnel is placed using an outside-in technique through a VMO muscle-splitting approach.

Surgical Technique for Anteromedial Approach and Outside-In Femoral Tunnels

This approach is selected when two femoral tunnels are used and is less traumatic than a muscle-splitting approach, because it is necessary to split the VMO for 5 to 6 cm for proper visualization, which is traumatic to the muscle tissue. In addition, this approach allows for good visualization of the graft and suture post fixation. When a single femoral tunnel is selected, this approach is not used; instead, a skin incision is placed directly over the drill guide and a limited muscle-splitting approach performed.

A vertical skin incision of 3 to 4 cm is made over the anteromedial vastus medialis proximal to the knee joint and just medial to the quadriceps tendon. When an ipsilateral QT-PB is harvested, the same skin incision is used (Fig. 21-16).

FIGURE 21-16 In this revision knee with a quadriceps autograft, the tendon harvest site is used to perform the subvastus approach. A, An incision is made at the vastus medialis obliquus (VMO)–retinacular attachment. B, The VMO is gently reflected proximally in an extra-capsular blunt dissection. If an allograft is selected, a smaller skin incision and approach are used.

The key to the anteromedial approach is to identify the VMO anterior attachment to the medial retinaculum and dissect in this plane, thereby avoiding the muscle and achieving a subvastus elevation of the VMO. Note that no incision is made into the VMO attachment to the patella and the medial patellofemoral ligament is not incised. Only a limited subvastus exposure is required. The synovium beneath the VMO is protected and not entered. The VMO nerve innervation proximally is not disturbed. A branch of the superior genicular artery that traverses the inferior border of the VMO is protected.

The outside location of the 1 o’clock femoral tunnel entrance is identified with the drill guide. The guide pin is placed 12 mm proximal to the articular cartilage of the medial femoral condyle and an equal distance medially from the medial trochlear border. The articular cartilage border is carefully palpated. The goal is to place a distal tunnel (and not a more proximal femoral entrance) to decrease graft tunnel angulation. The tunnel should be in line with the obliquity of the PCL graft, but not located too far distally adjacent to the articular cartilage to prevent a breakout of the tunnel into the distal femoral condyle. The location of the 4 o’clock femoral tunnel, to maintain an adequate bone bridge at both the entrance and the exit of both tunnels, is also 12 mm from the medial articular cartilage margin and just anterior to the femoral epicondyle.

At the time of graft fixation, the surgeon uses a headlight to view the graft in the tunnels. The graft length is observed as the knee is flexed, which determines the knee flexion angle at which the greatest graft length is produced. In addition, the headlight provides for adequate visualization for the placement of the interference screw and additional graft fixation. Routine closure is performed with absorbable sutures used for the synovium, VMO retinaculum attachment, and subcutaneous tissues.

PCL All-Inside Technique: One- and Two-Strand Graft Reconstructions

The authors’ graft preference for an all-inside technique is a QT-PB autograft for isolated PCL reconstruction. The preference for multiligament reconstructions is a B-PT-B allograft for the PCL procedure, using two femoral tunnels and a single tibial tunnel. The bone plug is placed and fixated in a posterior tibial tunnel or socket directly at the posterior entrance under fluoroscopic control (see Table 21-13). The goal is to match the results of the tibial inlay procedure, with the bone plug placed directly at the posterior PCL attachment using an oblique tunnel instead of a tibial inlay that requires an open posteromedial approach. The operative steps for these techniques are described in the following sections. The different PCL procedures and potential options for tibial and femoral placement and tunnels, based on the graft selected, are summarized in Table 21-14.

Patient Positioning and Setup

An examination under anesthesia is performed to confirm the diagnosis and carefully compare the injured knee with the opposite normal knee, as already described. It is important to palpate the medial tibiofemoral step-off at 90° of flexion in both knees. At surgery, the PCL grafts will be tensioned in knee flexion and the medial tibiofemoral step-off used as verification that the abnormal posterior translation has been corrected. In multiligament operative procedures, the patient is in a supine position with appropriate padding under all extremities with an Alverado foot and leg holder or similar device used to flex the knee joint to 60° to 70° (Fig. 21-17). This allows the lower limb to be secured and positioned throughout the operative procedures. After appropriate cruciate ligament surgery, any associated medial or lateral ligament procedure is performed with the knee flexion angle adjusted as necessary.

FIGURE 21-17 A, Patient position used in multiligament surgery with the foot in a leg holder and the knee flexed to 70°. B and C, Patient position with the knee flexed to 70° as an alternative position. Note the bed is flexed to maintain hip flexion. There is no pressure against the posterior popliteal space. The opposite leg is well padded.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: PATIENT POSITIONING AND SETUP

• Palpate medial tibiofemoral step-off (90° flexion) in both knees, will be used to verify correction of abnormal posterior translation at end of procedure.

• Multiligament procedures: patient supine position, padding under all extremities, device used to flex knee to 60°–70°, 4-inch flat padded bolster is placed underneath the operative thigh.

• Begin arthroscopy with pressure regulated pump: required to maintain joint distention.

• Routine arthroscopic anteromedial, anterolateral, and superolateral portals.

• Measure lateral and medial joint opening 20° flexion with gap test.

An alternative approach is used with isolated PCL surgery. The patient is placed supine on the operating table with appropriate padding. The operating table is placed in a 15° reflexed position to prevent hyperextension of the spine and produce mild flexion of the hip in order to relieve undue tension on the right and left femoral nerves. The knee portion of the bed is flexed to 60°. A thigh tourniquet is placed over cast padding. The opposite limb is positioned in a foam leg holder with the hip slightly flexed. A thigh-high compression hose is placed on the opposite extremity. After appropriate draping, a 4-inch flat padded bolster is placed underneath the operative thigh to protect the tissues and allow for knee flexion during the operative procedure. The operative procedure is performed with the knee flexed from 60° to 90°; however, further knee flexion is possible by adjusting the operative table or using an additional thigh bolster. It is important that no undue pressure is placed against the posterior thigh and sciatic nerve during the operative procedure. For this reason, an arthroscopic thigh holder is not used. In prolonged surgical cases, abnormal pressures on the posterior thigh may exist that compromise the neurovascular structures. As a result, posterior thigh muscle ischemia and peroneal tibial nerve damage (although rare) may occur.

When a meniscus repair is required, an arthroscopic thigh holder is initially used to allow for adequate joint opening for an inside-out meniscus repair using the previously discussed patient and limb positioning. The knee position of the bed is flexed as required. After the meniscus repair is performed, the thigh holder is removed and appropriate posterior thigh padding placed as necessary.

Arthroscopy of the knee begins with a pressure-regulated pump that is adjusted to provide mild joint distention and prevent fluid extravasation. The pump is required to maintain joint distention, particularly during the drilling of the tibial tunnel, so that the fluid expands the posterior capsule out of the operative field. Modern pressure- and volume-regulated pumps allow for a controlled inflow and outflow that maintains a safe pressure. In addition, sufficient fluid inflow is maintained so a tourniquet is not required during the operative procedure.

Routine arthroscopic anteromedial, anterolateral, and superolateral portals are created (Fig. 21-18). During the PCL reconstruction, a transpatellar central portal is required. The posteromedial portal to débride the PCL tibial fibers is not required and avoids inadvertent fluid extravasation into the popliteal fossa that would limit posterior capsule distention and posterior joint arthroscopic visualization.

FIGURE 21-18 Arthroscopic preparation of the tibial and femoral PCL graft sites through anteromedial, central, and anterolateral portals.

A standard arthroscopic examination is performed. The gap test is used to assess lateral and medial joint opening at 20° knee flexion with a varus and valgus stress as discussed. Any meniscus repairs or partial resections, débridement, or other arthroscopic procedures are performed. The PCL graft harvest procedure on the operative or contralateral limb is performed as required.

Tibial Tunnel Preparation

The most difficult part of the operative procedure is to prepare the tibial tunnel, located in the distal PCL attachment position, without injuring the popliteal neurovascular structures. In order to maintain joint distention and allow full visualization, a pressure-regulated arthroscopic pump is used and the femoral tunnels are placed after the tibia tunnel has been prepared.

The knee is positioned at 60° of flexion as described to prevent pressure against the popliteal structures posteriorly. This allows the posterior neurovascular structures to drop away from the posterior aspect of the knee. Matava and associates⁸³ reported that the mean distance of the PCL from the popliteal artery from 0° to 100° of flexion was 7.6 mm in the axial plane and 7.2 mm in the sagittal plane; however, individual variation may exist between knees. During the operative procedure, the surgeon is constantly aware of the joint pressure, fluid inflow and outflow, increased thigh tension, and any lack of joint distention. Intermittent palpation of the popliteal and calf region is performed during the operative procedure to detect fluid extravasation by an inadvertent puncture of the posterior capsule.¹¹¹

The preparation of the tibial tunnel is more difficult when the ACL is intact. It is first necessary to identify residual PCL fibers adjacent to the ACL, which are removed through the anteromedial portal with the arthroscope in the anterolateral portal. The middle genicular artery enters into the proximal aspect of the PCL and requires electrocoagulation. Some PCL fibers are left on the femoral attachment for later identification and placement of the graft tunnels. The anterior meniscofemoral ligament (aMFL) and posterior meniscofemoral ligament (pMFL) are identified and, if present, are preserved. It is usually possible to preserve the pMFL, but is more difficult to preserve the aMFL, especially when both meniscofemoral ligaments are present. When these ligaments are present, additional care is required in preparation of the tibial tunnels because the instruments are passed adjacent to these structures and the passage of grafts posteriorly may be temporarily blocked. If these structures impede visualization, they may be removed as long as the lateral meniscus has a confirmed posterior horn attachment to the posterior tibia and not an anatomic variant in which the posterior horn is attached by a meniscofemoral attachment.

The 30° arthroscope is next placed into the anteromedial portal and positioned high in the notch adjacent to the PCL femoral attachment. This allows the posterior capsular recess and remaining PCL stump at the tibial attachment to be viewed and instruments to be passed medial to the ACL.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: TIBIAL TUNNEL PREPARATION

• Knee 60° of flexion to protect neurovascular structures.

• Surgeon monitors joint pressure, fluid inflow and outflow, increased thigh tension, any lack of joint distention.

• Remove residual PCL fibers at femoral attachment, some fibers left for later identification and placement of the graft tunnels.

• 30° arthroscope placed into anteromedial portal, position high in notch adjacent to PCL femoral attachment.

• Pass curved elevator, gently free up space in front of and behind remaining PCL fibers.

• Protect medial and lateral meniscus posterior tibial attachments adjacent to the PCL tibial fossa.

• Remove PCL stump.

• View entire posterior PCL tibial fossa to identify correct placement of tibial tunnel.

PCL, posterior cruciate ligament.

A critical step is the passage of a curved Cobb elevator or commercially available Acufex (Smith and Nephew Endoscopy, Andover, MA) PCL Elevator (Fig. 21-19), which has a 90° curve and is used to gently free up the space in front of and behind the remaining PCL fibers. In some knees, the posterior capsule becomes adherent to the PCL fibers. The PCL Elevator is used to gently tease the capsule off of the PCL fibers and avoid rupture of the posterior capsule. This step requires a gentle approach to push the posterior capsule distally to the level of the distal PCL and capsule attachments, which are at the level of the posterior tibial step-off.

FIGURE 21-19 A and B, Tibial preparation. A 30° arthroscope is placed through the anteromedial portal. The scope is placed high in the notch adjacent to the medial condyle to view the posterior region of the joint. Instruments are placed through a central portal, medial to the ACL, carefully protecting the ligament. A, The Acufex PCL Elevator is inserted through the notch to carefully free the posterior capsule and re-create the normal capsular recess behind the PCL, because the capsule may be adherent to the ruptured PCL fibers. This step allows the capsule to displace posteriorly with fluid distention protecting the neurovascular structures. B, The tibial PCL stump is removed under direct visualization using curved shavers, baskets, Cobb elevators, and radiofrequency instruments. The posterior medial and lateral meniscus attachments are protected at all times. C, Anatomic illustration shows the close proximity of popliteal neurovascular structures.

If the posterior capsule is violated, a decrease in pump pressure is required and a large anterior fluid outflow portal is established. Close monitoring of any fluid extravasation into the popliteal space and calf is performed. It is usually safe to proceed under low-pressure conditions; however, if there is any question of visualization and popliteal space distention, the operative procedure is postponed to allow for capsule healing.

The medial and lateral meniscus posterior tibial attachments adjacent to the PCL tibial fossa are viewed and protected at all times during the preparation of the tibial tunnels. These meniscus attachments are located within a few millimeters of the PCL attachment and may be easily damaged during drilling of one or two tunnels.

The PCL stump is removed with arthroscopic instruments of the surgeon’s preference. There are a variety of curved instruments including baskets, suction cutting blades, and curets that are helpful. Particularly helpful are electrocoagulation instruments that are manually bent to an appropriate curve to facilitate removal of the PCL fibers in the posterior tibial fossa. At the conclusion of these steps, the entire posterior PCL tibial fossa (to the level of the posterior capsule attachment) is viewed for identification of the correct placement of the tibial tunnel.

Drilling of the Tibial Tunnel

A medial skin incision 3 to 4 cm is made 1 cm medial to the tibial tubercle. The tunnel entrance is medial or lateral to the tibial tubercle (Fig. 21-20). A theoretical advantage may exist for the tunnel to be started just lateral to the tibial tubercle to produce less posterior tunnel graft angulation. However, either tunnel location is acceptable. The senior author usually prefers an entrance medial to the tibial tubercle. When an ACL reconstruction is also performed with a medial tunnel, the PCL graft is placed through a tunnel lateral to the tibial tubercle.

FIGURE 21-20 Location of tibial tunnel. A, Tunnel position may be medial or lateral (dotted circle) to the tibial tubercle 3–4 cm distal to the joint line. The tunnel position is at a 50° or greater angle to decrease the acute angulation at the posterior tibia. B, Posterior tibial tunnel at the distal PCL attachment site. C, Acufex Director PCL Tibial Aimer is placed through the central portal with the tip of the guide resting on the posterior capsule insertion, with the target 5 mm proximal to the distal aspect of the PCL footprint. This allows sufficient tibial bone proximal to the tunnel to prevent anterior graft migration.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: DRILLING OF TIBIAL TUNNEL

• Medial skin incision 3–4 cm, 1 cm medial to tibial tubercle.

• Place arthroscope in anteromedial portal, position high in notch to view posteriorly.

• Place drill guide through transpatellar portal.

• Do not place guide pin too proximal in PCL fossa, produces vertical PCL graft.

• Place guide pin in distal central portion of PCL fossa.

• Angle drill guide 50°–55° to produce oblique tibial tunnel.

• Chuck guide pin to fixed distance with safety stop mounted on drill guide.

• Measure depth of guide pin to determine depth of drill penetration, confirm with fluoroscopy.

• Drill tip extends only 10 mm with a smooth shank, advance slowly. As drill tip reaches the posterior cortex, advance slowly.

• Chamfer proximal edge tibial tunnel.

• Remove any remaining PCL fibers.

PCL, posterior cruciate ligament.

The arthroscope is placed in the anteromedial portal and positioned high in the notch to view the posterior aspect of the tibial PCL attachment to the capsular attachment. In the majority of cases, the 30° scope provides an excellent view. On occasion, a 70° scope is required. An alternative approach is to place the arthroscope in a posteromedial portal and view the drill guide placed through the anteromedial portal. However, this is not recommended owing to the potential for posterior fluid extravasation.

The drilling of the tibial tunnel is shown in Figure 21-21. The drill guide is placed through the transpatellar portal. The tip of the guide is placed at the desired position of the tunnel as far distal as possible, which is to the level of the posterior capsule insertion on the tibia just before the posterior tibial step-off. The distal placement of the guide pin is a critical step for success; an error is to place the guide pin too proximal in the PCL fossa, which produces a near-vertical PCL graft with limited ability to resist posterior tibial subluxation. The tip of the guide rests on the distal posterior capsule attachment with the guide pin target just 5 mm proximal to the tip. This prevents the drill from proceeding too far distally beyond the posterior tibial step-off where the drill tip would not be visualized and could penetrate neurovascular structures. The goal is to place the guide pin in the distal central portion of the PCL fossa, 20 to 25 mm from the proximal entrance of the PCL fossa. This leaves 15 mm of the posterior fossa to retain the posterior graft position and prevent a vertical PCL graft. This is a key step of the procedure. The drill guide is angled 50° to 55° to produce an oblique tibial tunnel that will decrease graft angulation effects.

FIGURE 21-21 Drilling of tibial tunnel. A, Drill guide at the distal PCL attachment adjacent to the posterior capsule insertion. B, Acufex guide pin safety stop is attached to the drill guide. C, The guidewire is chucked on the power drill to the laser mark, which is the maximum length from the safety stop to the drill guide tip. This prevents the guidewire from being advanced beyond the drill guide after passing through the posterior cortex. D, Placement of the guide pin using the drill guide system at surgery. E, Fluoroscopy verifies guidewire placement. F, Tibial tunnel drilling with PCL Elevator/Wire Catcher to protect posterior neurovascular structures. G, Alternative technique using a “flip-drill” to make a posterior tibial socket for the PCL graft bone plug. Four fiberwire sutures placed through the plug are passed to the anterior tibia for graft fixation.

The next step involves use of the drill guide Safety Stop system (Acufex). The guide pin is chucked to a fixed distance with the safety stop mounted on the drill guide. The safety stop controls the depth of guide pin penetration into the tibia irrespective of the angle or position of the PCL tibial aimer and prevents the guide pin from passing beyond the guide tip and damaging neurovascular structures.

The guide pin is drilled into the selected tibial tunnel location. The depth of the guide pin is measured and used during the drilling process to determine the depth of drill penetration. The final position of the guide pin(s) is viewed and again confirmed that the guide pin is distal in the PCL fossa. Fluoroscopic confirmation of the guide pin position is recommended.

The tibial tunnel is drilled to the desired diameter using safety procedures, to be described. A commercially available PCL guide pin protector (Acufex) has a wide shape with a central recess 5 mm from its tip to engage the tibial guide pin before and during the drilling procedure. The tip of the pin is viewed at all times during the drilling process. The instrument prevents posterior migration of the pin and drill bit. The drilling process involves use of a drill with a drill tip and not a drill twist extending the length of the drill. The drill tip extends only 10 mm with a smooth shank. The drill is advanced in a slow manner. The depth of drill penetration is measured by the calibrated drill and prior drill guide pin measurements. As the drill tip reaches the posterior cortex, there is a noticeable resistance. At this point, the drill is slowly advanced without sudden penetration. A second option is to remove the power and place a hand chuck over the drill bit to complete the tunnel through the posterior tibial cortex.

When the flip-drill technique is selected, a 4-mm drill is initially used to establish the tibial tunnel. The flip-drill is then advanced under arthroscopic visualization to exit the posterior tibial tunnel. The drill is flipped and held against the posterior tibial cortex, and the tunnel is carefully drilled in a retrograde manner to the desired depth, which is determined by the measured length of the flip-drill (see Fig. 21-21). The PCL dilator remains in place posteriorly at all times to displace the posterior capsule away from the drilling procedure and prevent inadvertent capsule penetration.

To summarize, specific safety procedures are built into this technique to protect the neurovascular structures: (1) the drill guide system with the Safety Stop and controlled depth of guide pin penetration, with the guide pin placed 5 mm proximal to the distal posterior capsule insertion; (2) placement of the guide pin protector and slow drill penetration with direct viewing of the guide pin; (3) the final drill penetration of the posterior tibial cortex with complete protection posteriorly to prevent inadvertent deep drill penetration.

The proximal edge of the tibial tunnel is carefully chamfered with a rasp to limit graft abrasion effects (Fig. 21-22). Any remaining PCL fibers are removed so that the tibial tunnel entrance does not have soft tissue that would limit graft passage and to ensure the graft will lie flat against PCL tibial fossa. Again, it is necessary to have 15 mm of the posterior tibial fossa and an intact posterior intraspinous area proximal to the tunnel to maintain the normal angulation of the PCL tibial attachment to prevent a vertical PCL graft and to decrease graft tunnel enlargement (windshield-wiper effect). The most common technical mistake is to place the tibial tunnel at the proximal entrance of the PCL fossa, which is proximal to the native PCL tibial attachment.

FIGURE 21-22 Chamfering of the tibial tunnel with a rasp to decrease graft abrasion effects. It is necessary to have 15 mm of bone retained in the posterior tibial fossa above the PCL footprint to prevent the graft from migrating through the tibia.

PCL Femoral Graft Technique

An important aspect of a successful PCL reconstruction is to have a clear understanding of PCL anatomy and changes in fiber-length and tension with knee flexion, as already described. The anatomic rule of thirds to describe the PCL attachment assists the surgeon in defining the anterior-to-posterior plane and the proximal-to-distal plane of the native PCL (see Fig. 21-8A and B).

As described previously, the PCL attachment is elliptical in shape, extending from high in the notch over the lateral aspect of the distal medial condyle from an approximate 11:30 to 5 o’clock position (left knee). The PCL footprint follows the articular cartilage, with the anterior portion within 2 to 3 mm of its edge depending on the reference system used as previously discussed.⁸⁷ At the 4 o’clock position, the PCL attachment is approximately 4 mm from the articular cartilage edge.¹²⁹ However, if the aMFL is present, the footprint will appear to be 1 to 2 mm from the cartilage edge. There is anatomic variability in the normal proximal-to-distal width of the PCL, and in some knees, a more oval appearance exists owing to an increased width of the middle third of the PCL attachment. Because of anatomic variability in the PCL femoral attachment, it is necessary to map out the attachment using remaining PCL fibers to locate the desired graft position. The reference system axis used to describe the PCL attachment is distal-to-proximal and anterior-to-posterior with the knee in full extension. However, the surgeon views the PCL with the knee flexed and it is also helpful to communicate a graft position as “deep” or “shallow” and “high” or “low” in the femoral notch on the medial femoral condyle.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: POSTERIOR CRUCIATE LIGAMENT FEMORAL GRAFT TECHNIQUE

• Anatomic rule of thirds used to define anterior-to-posterior and proximal-to-distal planes of native PCL.

• PCL footprint follows articular cartilage, anterior portion within 2–4 mm of its edge.

• At 4 o’clock position, PCL attachment is 4 mm from articular cartilage edge.

• If anterior meniscofemoral ligament present, footprint appears to be 1–2 mm from cartilage edge.

PCL, posterior cruciate ligament.

Two main techniques are used for PCL graft femoral placement and fixation. The first technique (authors’ preference) incorporates two separate femoral tunnels with two separate graft strands. The second technique involves a single femoral tunnel when operative time and complexity of the surgery are factors.

Technique for Femoral Placement of Two Tunnels and Graft Passage

The technique for femoral placement of two tunnels and graft passage is shown in Figure 21-23. The PCL footprint is mapped with a calibrated probe and electrocoagulation. The 12 o’clock, 1 o’clock, and 4 o’clock position marks on the medial femoral condyle are made. The goal is to create two separate femoral tunnels in the distal two thirds of the native PCL attachment. This places a graft with an approximate 100 mm² in cross-section, occupying up to 75% of the PCL attachment.

FIGURE 21-23 Placement of two femoral tunnels. A, Arthroscopic view of two PCL attachment sites shows 1 o’clock and 4 o’clock guide pin marks, 6 and 8 mm from the articular cartilage. B, PCL guide 15 mm proximal to the outside articular cartilage border. C, Placement of the 1 o’clock tunnel. D, Placement of the 4 o’clock tunnel.

If the PCL graft is placed too distal or shallow in the notch, it will be subject to high tensile forces with knee flexion resulting in constraining flexion and probable graft failure. If the graft is placed too proximal or deep in the notch, the graft will slacken with knee flexion and allow posterior tibial subluxation. The correct placement within the PCL footprint is shown in Figure 21-23 where the graft replaces the distal two thirds of the PCL that functions in resisting posterior tibial subluxation with knee flexion.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: TECHNIQUE FOR FEMORAL PLACEMENT OF TWO TUNNELS AND GRAFT PASSAGE

• Map PCL femoral footprint, mark 12 o’clock, 1 o’clock, and 4 o’clock positions.

• Two separate femoral tunnels in distal two thirds native PCL attachment; anterior 1 o’clock, posterior 4 o’clock.

• Femoral tunnels drilled outside-in approach (VMO-sparing technique).

• Core reamer used for 1 o’clock tunnel.

• 20-gauge wire passed through tibial tunnel, out anterolateral portal.

• 22-gauge wires passed through separate femoral tunnels, out anterolateral portal.

• Tibial bone plug passed in joint, assist with nerve hook to orient graft to enter tibial tunnel.

• Pass two femoral graft strands, confirm correct placement.

• Confirm placement bone plug with fluoroscopy, arthroscope.

• Tie sutures to tibial suture post. Final interference screw fixation fluoroscopic control.

PCL, posterior cruciate ligament; VMO, vastus medialis obliquus.

The PCL guide is used for two separate femoral tunnels to prevent overlap of the tunnels. The anterior tunnel is centered at the 1 o’clock position, 6 mm deep to the articular cartilage. The posterior tunnel is centered at the 4 o’clock position, 8 mm proximal (deep) to the articular cartilage edge. A mark is made at the center position of each tunnel with cautery, and then defined with a curet or sharp awl passed from the anterolateral portal. The bone beneath the PCL attachment is dense and requires making a well-defined, small entrance hole for the two drill guide pins. Following this technique, the first tunnel is located in the anterior third of the PCL attachment and in the distal two thirds in the proximal-to-distal direction. The second tunnel is located in the posterior third of the PCL attachment, also in the distal two thirds. The tunnels are carefully placed in the anterior-to-posterior direction to allow for a 2- to 3-mm bone bridge between tunnels. This placement of the two tunnels ensures that both graft strands will resist posterior tibial translation with knee flexion, sharing the load and not placed too deep in the notch.

The two femoral tunnels are drilled using the outside-in (VMO-sparing approach) subvastus technique. As already described, the entrance of the 1 o’clock tunnel is 12 mm proximal to the femoral articular cartilage border and medial to the trochlea. The 4 o’clock tunnel entrance is also 12 mm proximal to the articular cartilage border and anterior to the femoral epicondyle. A core reamer is used for the 1 o’clock tunnel to obtain a bone graft for the patellar defect (QT-PB graft; Fig. 21-24). Careful chamfering of the tunnel edges is performed to decrease graft abrasion. A flexible ruler is passed through the tibial and femoral tunnels to measure the intra-articular length of the two graft strands.

FIGURE 21-24 A, Use of the core reamer to obtain the bone graft for a patellar bone defect. B, Arthroscopic view shows final appearance of two femoral graft tunnels.

The passage of the graft is performed in a stepwise fashion (Fig. 21-25). A 20-gauge wire is passed through the tibial tunnel and brought out the anterolateral portal, which is enlarged sufficiently to accept the PCL graft. A 22-gauge wire is passed through each of the two femoral tunnels and a grasper or nerve hook is used to bring the two wires out the same anterolateral portal. The 1 o’clock and 4 o’clock wires are marked.

FIGURE 21-25 A, Passage of the quadriceps-bone two-strand graft through the enlarged anterolateral portal. B, Final appearance of the two-strand graft within the femoral tunnels.

The tibial bone is first passed into the knee joint with the arthroscope placed in the anteromedial portal. A nerve hook facilitates passage adjacent and medial to the ACL and into the tibial tunnel. It is important that all soft tissues have been removed about the tibial tunnel, which is 1 mm larger than the graft to facilitate passage. The nerve hook is used to angle the bone to facilitate the initial entrance into the tibial tunnel. The two femoral graft strands are then passed through the enlarged anterolateral portal and viewed through the anteromedial portal to have the correct orientation in the 1 o’clock and 4 o’clock tunnels. It is preferred to first pass the 4 o’clock and then the 1 o’clock graft.

Fluoroscopy is used to confirm final placement of the bone plug in the tibial tunnel (Fig. 21-26). The graft is marked at the collagenous fiber-bone junction and viewed arthroscopically to confirm that the bone plug is entirely within the tibial tunnel and placed directly at the posterior tibial tunnel entrance. The sutures are tied over a tibial suture post. An absorbable interference screw (1 mm less than the diameter of the tunnel) is used for bone plug fixation at the tibial tunnel, verified by fluoroscopy. The final tensioning of the graft at the femoral site is performed next. In the alternative flip-drill technique of drilling a posterior tibial socket, four high-strength sutures placed in the bone plug are tied over a suture post.

FIGURE 21-26 Fluoroscopy confirms that the patellar bone plug is directly at the posterior tibial tunnel exit.

Graft Tensioning and Fixation for All-Inside Grafts

The graft tensioning and fixation steps are the same for all grafts. For grafts with the bone block in the tibial tunnel, initial fixation is performed at the tibia (as already described) and final tensioning and fixation are performed at the femoral site. For bone blocks placed at the femoral site, fixation is first performed at the femoral site and final tensioning and fixation performed at the tibial site (Fig. 21-27).

FIGURE 21-27 Anteroposterior (A) and lateral (B) radiographs of a PCL two-strand QT-PB reconstruction using a single tibial tunnel with the bone plug (dotted) placed in the posterior tunnel exit with fixation by an absorbable interference screw and suture post. Femoral tendon fixation is with a separate absorbable interference screw in each tunnel and a suture post (staple).

After the initial fixation of the graft at either the femoral or the tibial site, the knee is taken through a full range of motion with an assistant displacing the tibia forward to correct for the weight of the leg and maintain joint reduction.

The knee flexion position for graft fixation is checked by determining the flexion angle at which the graft strand is the longest (functional zone) to ensure that the graft is not tensioned in its shortest position, which would overconstrain the joint and produce graft failure. A nonserrated hemostat is placed on each set of graft strand sutures exiting from either the femoral or the tibial tunnel(s) and circumferentially wound onto the clamp. The clamp is used to apply 10 pounds (44 N) of load to each graft. The grafts are conditioned by taking the knee joint through 0° to 120° of flexion. The knee is placed at 90° flexion and a normal medial tibiofemoral step-off is palpated and confirmed. This is done with the assistant placing approximately 10 pounds (44 N) of pressure against the calf to apply an anterior tibial force (assuming the ACL is intact). The knee is again taken through a full range of motion and the change in length of both graft strands noted. With increasing knee flexion, there will be increased tension and a pulling of the sutures and clamp into the tunnel of only 0 to 2 mm as the 90° position is reached.

The graft is longest at high knee flexion angles, which is the position selected for graft fixation. In most knees, the 70° flexion angle has the same graft length behavior as 90° and this position is selected. Commercial graft-tensioning devices⁴² are available (as used in ACL reconstructions) that provide measurable length-tension data and may be used for measurement of graft-tensioning loads. The sutures for each graft stand are tied over a femoral or tibial post, maintaining the 10 pounds of graft load and 10 pounds of anterior tibial load.

The final position of the medial tibiofemoral joint is again verified. An absorbable interference screw is added to the fixation. The arthroscope is again placed and with a nerve hook, the tension in the PCL graft(s) is confirmed. The knee is taken through 0° to 110° flexion.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: GRAFT TENSIONING AND FIXATION FOR ALL-INSIDE GRAFTS

• Grafts bone in tibial tunnel: initial fixation at tibia, final tensioning and fixation at femoral site.

• Grafts bone at femoral site; initial fixation at femoral site, final tensioning and fixation at tibial site.

• After initial fixation, knee taken through full range of motion.

• Check knee flexion position for graft fixation by determining the flexion angle at which the graft strand is the longest.

• Condition graft 0°–120° flexion.

• Verify normal medial tibiofemoral step-off at 90°.

• Tie sutures for each graft stand over femoral or tibial post, verify final position of medial tibiofemoral joint. Absorbable interference screw added.

• Use arthroscopically-placed nerve hook to confirm tension in PCL graft strands.

• With ACL reconstruction

Tension PCL graft, avoid anterior tibial subluxation.

Verify tibiofemoral position at 0° and 90° and graft tension with extension-flexion.

Confirm arthroscopic normal femoral condyle, anterior medial and lateral meniscus relationship

ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.

Whereas techniques for the second posterior tunnel to be placed in a deeper, more proximal position have been described in the literature, the authors recommend placing the tunnels in the middle and distal two thirds of the PCL attachment, as described. This allows both graft strands to share the loading, and therefore, tensioning is at the 70° flexion position for both grafts.

It should be noted that if one or both femoral tunnels are too proximal (deep in the notch), the graft strand length decreases with knee flexion (allowing posterior subluxation) because the graft strand is longest closer to full extension. In this situation, the final graft fixation is done at the more extended position. The more proximal graft will function in a reciprocal manner and the desired load-sharing between grafts will not be achieved.

Alternatively, if the graft tibiofemoral attachment length is longer at 45° to 60° of knee flexion, as the graft is pulled into the tunnel with knee flexion, the femoral tunnels are too distal (shallow). This is not an acceptable position and the femoral tunnel is reconfigured, removing 5 mm of the proximal aspect of the tunnel to allow the graft to assume a deeper and more correct position. The interference femoral screws are placed distal in the femoral tunnels to secure the grafts in a more proximal (deep) position. With the technique described in the placement of the femoral tunnels, it would be rare for this graft tunnel adjustment to be performed.

In knees that undergo ACL reconstruction, it is important to determine as accurately as possible the neutral AP position of the medial and lateral tibiofemoral joints (without added internal or external tibial rotation). There is a tendency to displace the tibia into an abnormal anterior position by overtensioning the PCL graft. When the ACL is intact, the graft forces displace the tibial anteriorly, loading the ACL under low loads. When the ACL is insufficient, the following steps are performed to prevent anterior tibial subluxation:

1 Place the knee at full extension with a 10-pound (44 N) force on each graft (or 20 lb for a single graft) and 10 pounds anterior force on the calf to overcome gravity weight effects of the leg. This achieves a reduced tibiofemoral joint position when one or both of the medial or the fibular collateral ligaments (FCLs) are present.

2 Flex the knee to 90°, maintaining the same approximate graft load and anteriorly directed load on the calf. An anteriorly subluxated tibia at 90° (compared with 0°) will have abnormally increased tibiofemoral attachment site distances, and the graft can be observed to piston into the tibial tunnel. In essence, the graft should be nearly similar in its tibial position at both 0° and 90° of flexion.

3 Palpate for a normal tibiofemoral step-off and arthroscopically visualize a normal anterior relationship of the anterior portion of the medial and lateral meniscus in relationship to the respective femoral condyles. If there is any question, a lateral fluoroscope or radiograph may be obtained intraoperatively. This is especially helpful in large limbs in which the neutral AP position is difficult to determine with accuracy.

Femoral Placement of a Single Tunnel: Outside-in Technique

The drill guide is introduced into the anteromedial portal and the desired femoral tunnel position is located. The arthroscope is placed in the anterolateral portal. The goal is to place the tunnel into the anterior half of the PCL attachment, avoiding too proximal a placement. The entrance of the guide pin is at the 2 o’clock position and approximately 7 to 8 mm from the articular cartilage edge. This should produce a tunnel that is 2 to 3 mm from the articular cartilage edge. A note of caution is that there is a tendency to place the drill tunnel too proximal (deep in femoral notch) and out of the PCL femoral footprint, producing a graft that functions only at low flexion angles. The ability to carefully determine the native PCL footprint in the patient’s knee is important for correct tunnel placement. The preference is for a tunnel of 10 mm in most knees and 11 mm in larger knees. If the drill diameter is larger, portions of the graft will be too deep in the notch and outside of the normal PCL footprint.

Critical Points POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUE: FEMORAL PLACEMENT OF A SINGLE TUNNEL: OUTSIDE-IN TECHNIQUE

• Drill guide in anteromedial portal, locate desired femoral tunnel position.

• Entrance of guide pin: 2 o’clock position, 7–8 mm from articular cartilage edge.

• Tunnel size: 10 mm in most knees, 11 mm in larger knees.

• Small skin incision, VMO muscle-splitting approach.

• Over-ream guide pin or use coring reamer to harvest bone graft.

• Chamfer tunnel entrance into knee joint.

• Graft passage: inside-out or outside-in.

• Femoral graft fixation outside-in, interference screw.

• Prior to graft fixation, adjust graft in length to place the bone block adjacent to femoral attachment.

• All grafts at tibia have double fixation with a cancellous interference screw and suture post.

• Use single-tunnel technique when operative time limited, less technically demanding approach necessary.

VMO, vastus medialis obliquus.

The entrance position of the guide pin in the outside-in technique is midway between the femoral epicondyle and the trochlea, at least 12 mm proximal to the articular cartilage edge. A more proximally placed guide pin would increase the tunnel angulation entering the joint and potentially increase graft abrasion effects.

A small skin incision and VMO muscle-splitting incision are made. A larger incision is not required because the bone block fixation is done with a cancellous screw without an added fixation device. The guide pin is over-reamed, or alternatively, a coring reamer may be used to harvest a bone graft. The tunnel entrance into the knee joint is chamfered to limit graft abrasion effects. A modification of this technique is used with a B-PT-B allograft in which a flip-drill is placed from outside-in instead of the guide pin and the femoral socket drilled from outside-in. This is an easier technique than placing the femoral tunnel from inside-out, as already described. When a femoral or tibial socket is placed with the flip-drill, the technique involves overdrilling the socket depth so that graft position and tensioning are possible.

At the time of graft passage, either an inside-out passage (enlarged anterolateral portal used for graft passage into the knee) or an outside-in passage (retrograde guidewire from tibial tunnel out through femoral tunnel) is used. Femoral graft fixation is easily performed in an outside-in manner with an interference screw of the surgeon’s preference. Newer absorbable interference screws provide stable fixation. Prior to graft fixation, the graft is adjusted in length to place the bone block adjacent to the femoral attachment to limit fiber abrasion. The surgeon uses a headlight and adequate exposure to advance an interference screw into the anterolateral aspect of the femoral tunnel for graft fixation. Arthroscopic examination confirms that the screw is not advanced into the knee joint. The final graft conditioning, tensioning, and fixation are the same as previously described. All grafts at the tibia have double fixation with a cancellous interference screw and suture post.

Publications describe the all-inside drilling of a large single tunnel at the femoral attachment. However, the outside-in approach is preferred for large-diameter tunnels. From a technical standpoint, the drilling of a large-diameter tunnel is difficult owing to the proximity of the lateral condylar articular cartilage and the ACL, and the tendency exists to have a tunnel entrance that is markedly angled distally. In the authors’ experience, a more precise and less angulated tunnel is obtained with the outside-in approach. The single femoral tunnel technique is used when operative time must be limited because this approach is the least technically demanding of all approaches for PCL femoral graft fixation.

Alternative PCL All-Inside Techniques

Femoral Placement of Rectangular (Oval) Tunnel for Bone Plug

An all-inside technique using the QT-PB autograft or B-PT-B or AT-B allograft is described in which the bone plug is placed at the femoral site and the soft tissue graft is placed through a tibial tunnel. This procedure has the advantage of easy passage of the soft tissue graft through the posterior tibial tunnel. This is used in select knees in which operative time is a factor. In addition, in revision knees, there may be displaced femoral tunnels in which the bone plug provides a more stable fixation at the femoral site. As already discussed, the senior author has a preference to reverse the graft with the bone plug at the posterior tibial tunnel. It is unknown from a clinical standpoint which procedure provides the best outcome related to return of joint stability.

Critical Points ALTERNATIVE POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUES: FEMORAL PLACEMENT OF RECTANGULAR (OVAL) TUNNEL FOR BONE PLUG

• Bone plug placed at femoral site using rectangular femoral slot or femoral tunnel, soft tissue graft placed through tibial tunnel.

• Use when operative time is a factor, revision knees.

• Goal: create 8- × 12-mm rectangular slot extends from 1 to 4 o’clock in distal two thirds of PCL attachment.

• Mark 12 o’clock, 4 o’clock positions on medial femoral condyle.

• 2.4-mm guide pin placed through anterolateral portal, knee flexed 90°, advance through medial femoral condyle 25 mm in depth.

• Place second guide pin, over-ream with endoscopic drill.

• Avoid lateral femoral condyle articular cartilage as the drill is introduced into knee joint.

• Use PCL Dilator to dilate attachment into oval 9- × 13-mm shape.

• Chamfer and rasp distal aspect femoral oval opening.

• 22-gauge wire passed through tibial tunnel, bring out through anterolateral portal.

• Pass soft tissue ends of graft through enlarged anterolateral portal.

• Use nerve hook through anteromedial portal to assist graft passage.

• Pass guide pin through anterolateral portal into rectangular femoral slot to exit anterior and proximal to medial femoral epicondyle.

• Pass bone block with sutures into the knee joint. Arthroscopically visualize bone block to ensure cancellous surface is flush at femoral attachment.

• Femoral fixation: interference screw, knee flexed 110°.

• Tibial fixation: interference screw and suture post.

PCL, posterior cruciate ligament.

The patient positioning and initial surgical approach are similar to the all-inside technique just described. The posterior PCL stump is removed and PCL tibial attachment prepared for one or two tibial tunnels.

When a two-strand PCL reconstruction is selected with the collagen graft strands placed in a tibial tunnel, using two tibial tunnels is advantageous owing to the smaller-diameter tunnel required. This avoids creating a large-diameter single tunnel in which both graft strands are passed. Two smaller-diameter tunnels provide for better healing potential and in-growth into the graft than a single large-diameter tunnel as already described. The two tibial tunnels are placed on the medial and lateral aspects of the tibial tubercle. The only knees in which two tunnels are difficult to drill are small knees in which the width of the PCL attachment is narrow and a single tunnel is required. Otherwise, it is possible to place two 7- or 8-mm tunnels side-by-side at the distal PCL attachment site and avoid the posterior meniscus attachments. In multiligament reconstructions when operative time is a factor, a single tibial tunnel is selected. The single tibial tunnel (or double tunnels) is drilled with the technique previously described.

The technique for the femoral PCL graft attachment of the bone portion of the graft involves using either a rectangular femoral slot or a femoral tunnel. The all-inside technique for the rectangular slot is preferred to place a greater portion of the graft within the PCL femoral footprint, in which approximately three fourths of the footprint is occupied by the graft. A single circular tunnel of 10 to 11 mm replicates only the anterior and middle portions of the PCL attachment and is less ideal from a theoretical standpoint.

The goal is to create an 8- × 12-mm rectangular slot that extends from 1 o’clock to 4 o’clock in the distal two thirds of the PCL footprint. The 12 o’clock and 4 o’clock marks are made on the medial femoral condyle. Again, the guide pin mark is 6 and 8 mm from the articular cartilage of the medial femoral condyle for the anterior and posterior tunnels (Fig. 21-28), verified by observing the PCL footprint and that the two tunnels are in the distal two thirds of the footprint. Use a small curet or awl to penetrate and define the pilot hole for each tunnel. A 2.4-mm guide pin is placed through the anterolateral portal into the anterior tunnel location, the knee flexed to 90°, and the guide pin advanced through the medial femoral condyle approximately 25 mm in depth based on the patellar bone length.

FIGURE 21-28 A and B, All-inside femoral tunnel. The PCL Femoral Template is placed through the anteromedial portal with the arthroscope in the central portal and defines the position of two overlapping 7- or 8-mm tunnels. The top edge of the template is placed 2 mm from the articular margin and the bottom edge is 4 mm from the articular margin. This places the center of the anterior tunnel 6 mm from the articular cartilage margin and the center of the posterior tunnel 8 mm from the articular cartilage margin.

The second guide pin is placed into the second marked position. The guide pins are over-reamed with an endoscopic drill (Fig. 21-29) to form an oblong tunnel entrance to a depth corresponding to the graft bone. Care is taken to avoid the lateral femoral condyle articular cartilage as the drill is introduced into the knee joint. The remaining central bone bridge is removed with a curet or bur.

FIGURE 21-29 The guide pins are placed and then over-reamed with an endoscopic drill to a depth of 25 mm, avoiding passage of the drill through the femoral cortex. The central bone bridge is removed with a curet and bur.

The PCL Dilator (Fig. 21-30) dilates the attachment into an oval 9- × 13-mm shape that is approximately 1 mm larger than the bone portion of the graft. Care is taken at this point to use low forces in dilating the rectangular slot to avoid fracture of the femoral condyle. In the authors’ experience, this has not been reported; however, it is worth a cautionary note. The PCL Dilator has a graft-sizing slot on the handle for a 9- × 13-mm bone block to assist in preparation of the graft.

FIGURE 21-30 The PCL Dilator is used to gently conform the femoral oval footprint to 9 x 13 mm and to an appropriate depth. There is a matching oval opening in the PCL Dilator handle of 9 × 13 mm to size the bone block.

The distal aspect of the femoral oval opening is chamfered and rasped to create a gentle slope to limit graft abrasion.

It should be noted that the femoral tunnel is oval in the final appearance, approximating two thirds or more of the PCL attachment site. The bone portion of the graft is rectangular, although the graft corners may be contoured to a more oval shape for easier passage into the femoral tunnel.

The passage of the graft begins with the passage of a 22-gauge wire through the tibial tunnel, which is grasped with a nerve hook and brought out through the anterolateral portal (Fig. 21-31). The tendon graft strands are passed through the enlarged anterolateral portal, which is increased 2 to 3 cm in length to prevent soft tissues from impeding graft passage. When a two-tunnel tibial technique is used, two wires are passed and the graft strands marked for the 1 o’clock graft to the lateral tunnel and the second 4 o’clock graft to the medial tibial tunnel. A towel clip or suture is used to close the anterolateral portal after graft passage to maintain joint distention.

FIGURE 21-31 All-inside graft passage. A 20-gauge wire is passed through the tibial tunnel and grasped anteriorly through the anterolateral arthrotomy. The tibial portion of the graft is passed through the single tibial tunnel. The pin is then passed through the anterolateral portal into the femoral tunnel. The bone block is passed through the enlarged anterolateral portal and carefully oriented into the correct position with the cancellous bone surface oriented deep in the oval opening.

The graft strands are viewed through the anterolateral portal adjacent to the ACL (when present), and a nerve hook through the central portal is used to gently assist and angulate the graft to enter into the respective tibial tunnel. It is easier to first pass the medial graft strand and then the lateral graft strand, maintaining the orientation of the bone portion of the graft so the lateral tibial strand corresponds to the 1 o’clock femoral position and the medial tibial strand corresponds to the 4 o’clock femoral position.

A guide pin (with an end to carry the sutures) is passed through the anterolateral portal into the rectangular femoral slot to exit anterior and proximal to the medial femoral epicondyle. The bone block with sutures is passed into the knee joint. The arthroscope views the bone block and the orientation is controlled with the cancellous surface oriented proximal (deep) in the rectangular slot. The bone block is positioned flush (not recessed) at the femoral attachment. Fixation is performed with an interference screw passed through the anterolateral portal with the knee flexed to 110° (Fig. 21-32). The interference screw is placed anterior to the bone block and snugly secures the graft.

FIGURE 21-32 The final configuration of the single (A) or alternative two-tunnel (B) technique.

The conditioning and graft tensioning is the same as described for the all-inside technique, except the final fixation is performed at the tibial site with an interference screw and suture post.

Two Separate Femoral and Tibial Tunnels and Two Separate Grafts

This technique uses two separate B-PT-B grafts, one autograft and one allograft. The tibial and femoral outside-in tunnels are placed and drilled as already described. The passage of the two bone grafts is technically more demanding when the ACL is present and requires patience. Two tibial tunnel guidewires are passed and brought out the anterolateral portal. The medial tibial (4 o’clock) femoral graft is first passed with the tibial portion gently eased into the tibial tunnel. The femoral bone plug with a 4-cm loop lead suture is advanced through the anterolateral portal into the knee joint. A suture retrieval instrument is used at the posterior 4 o’clock femoral tunnel to grasp the suture and gently lift the bone block into the tunnel, assisted with a nerve hook. The scope is placed in the central or anterolateral portal to view correct placement of the femoral bone. The procedure is repeated for the lateral tibial 1 o’clock femoral graft. It is important in the preparation of the femoral tunnel that all soft tissues in the posterior aspect of the notch behind the PCL femoral attachment be removed to allow for the graft to pass and to provide sufficient visualization.

Critical Points ALTERNATIVE POSTERIOR CRUCIATE LIGAMENT ALL-INSIDE TECHNIQUES: TWO SEPARATE FEMORAL AND TIBIAL TUNNELS AND TWO SEPARATE GRAFTS

• Use two separate B-PT-B grafts: one autograft and one allograft.

• Tibial and femoral tunnels are placed and drilled as already described.

• Two tibial tunnel guidewires passed, brought out the anterolateral portal.

• Medial tibial 4 o’clock femoral graft first passed.

• Femoral bone block with 4-cm loop lead suture passed through anterolateral portal.

• Procedure repeated for the lateral tibial 1 o’clock femoral graft.

• Each bone plug fixed with interference screw.

• All-inside placement of femoral tunnels

Graft passage same order except femoral portion of graft advanced through anterolateral portal by guide pin-–suture carrier placed through the respective femoral tunnel.

Interference screw fixation through anterolateral portal for each graft.

Femoral interference screw anterior to 1 o’clock graft strand and distal (shallow) to 4 o’clock graft strand.

After appropriate tensioning, final tibial fixation with interference screw and suture post.

B-PT-B, bone–patellar tendon–bone.

Through the anteromedial approach for the VMO, the outside aspects of the femoral tunnels are visualized. Through the arthroscope, the bone block is placed flush with the femoral tunnel opening within the joint. Each bone block is fixed with an absorbable interference screw. The visualization of the bone block deep in the tunnel is facilitated by use of the surgeon’s headlight and graft position verified by arthroscopy. In revision knees or when obvious femoral bone osteopenia is present and the fixation compromised, a suture post is used for added fixation with the sutures placed in each bone block.

In the all-inside placement of the two femoral tunnels for two separate bone plugs when a B-PT-B graft is used, the graft passage is in the same order except the femoral portion of the graft is advanced through the anterolateral portal by a guidewire–suture carrier placed through the respective femoral tunnel. Interference screw fixation is performed through the anterolateral portal for each graft strand with the knee flexed to 110°. The final placement of the bone block in the femoral tunnel is more ideal (less graft angulation) when the cancellous side of the bone block is posterior (deep) and the bone advanced flush with the femoral tunnel. Graft conditioning, tensioning, and fixation are performed as already described. The femoral interference screw is placed anterior to the 1 o’clock graft strand and distal (shallow) to the 4 o’clock graft strand, and after appropriate tensioning, the final fixation is performed at the tibial site with an interference screw and suture post.

The senior author has used this technique, and publications occasionally reference this procedure using a variety of grafts. The recommendation provided in this chapter is to use a single tibial tunnel with a bone plug without the added complexity of two tibial tunnels.

PCL Arthroscopic-Assisted Open Tibial Inlay Technique

Patient Positioning and Setup

An examination under anesthesia of both knees is performed to confirm the preoperative diagnosis and detect any subtle instability. The medial tibiofemoral step-off at 90° flexion with a posterior tibial load is noted and the joint reduced to normal and compared with the uninvolved knee. The reduced position and normal medial tibiofemoral step-off will later be reproduced with graft tensioning. Varus-valgus and tibial rotation tests for joint subluxation are performed as already described and compared between involved and uninvolved knees because concurrent ligament injuries, particularly to the posterolateral structures, are frequent and require reconstruction.

The patient is placed in a supine position on an inflatable beanbag (Fig. 21-33). The distal end of the beanbag is placed at the gluteal crease so it does not interfere with the tourniquet and the external rotation of the lower limb during the posteromedial tibial inlay approach. The beanbag is inflated and contoured to the patient’s thorax and pelvis. A safety belt and kidney rest are placed to further secure the patient to the operating table when it is externally rotated (operative side down) during the posteromedial approach. A thigh tourniquet is placed over cast padding and used only intermittently for short periods during graft harvest and the posteromedial approach. The table is reflexed at its midpoint to decrease spine hyperextension, produce mild hip flexion, and prevent tension on the femoral nerve from a hip hyperextension position. The opposite extremity is placed in a thigh-high compression hose and posterior padded leg support to avoid hip hyperextension or abnormal pressures on the posterior thigh during the operative procedure.

FIGURE 21-33 Patient positioning. The patient is in a supine position with an inflatable beanbag, safety belt, and kidney rest (not shown) to secure the patient to the operating table.

The correct positioning of the operative extremity deserves special emphasis as described. During prolonged arthroscopic-assisted procedures, pressure on the posterior thigh may interfere with the vascular supply of the biceps muscle and peroneal nerve, and although rare, muscle necrosis and nerve injury have been reported. A leg holder is not used unless a meniscus repair is required, at which time, the leg holder is used initially to allow adequate tibiofemoral joint opening and is then removed for the remainder of the operative procedure.

General anesthesia is used and a urinary catheter placed when multiple operative procedures will be performed and the anesthesia time prolonged. Even though all dislocated knees have vascular consultation and ankle/brachial index studies, if there is any question of diminished pulses or vascular supply, the foot is draped in a sterile plastic bag to allow palpation of pulses and observation of color during the operative procedure.

The initial arthroscopic procedure is performed to thoroughly examine the knee joint including patellofemoral tracking, articular cartilage lesions, and medial and lateral tibiofemoral joint opening gap tests to exclude associated ligament injuries. At this time, débridement or meniscus procedures are performed as required. A pressure-regulated inflow and outflow arthroscopic pump is necessary, and joint distention is monitored continuously by the surgeon. The arthroscopic pump is set to the lowest pressure and volume for visualization, which avoids the requirement of a tourniquet.

The autograft harvest procedure or preparation of the allograft is completed as described.

Posteromedial Approach^91,102,110

With the patient in a supine position, the posteromedial aspect of the knee is viewed by rolling the table 25° with the operative side in the down position. The tourniquet is inflated. A partial figure-four knee position is assumed (45° external hip rotation, 45° knee flexion). The operative limb is elevated and the foot placed on a padded (pillow) Mayo stand to lift the knee away from the table. An assistant externally rotates the foot and controls the lower limb position on the Mayo stand during the procedure. The surgeon and assistant are seated at the side of the operative table directly viewing the entire posteromedial aspect of the knee. Operative headlights are used.

An alternative approach is for the surgeon to be seated between the patient’s lower extremities by flexing the knee portion of the table and elevating the nonoperative limb into a flexed and abducted position. The senior author has not found it necessary to use this position. In either of the two limb positions, one person must be dedicated to maintain the operative limb in a safe elevated and externally rotated position supported by the padded Mayo stand.

Numerous surgical approaches that provide access to the popliteal fossa PCL tibial attachment have been described.^{1,8,9,15,86,89,152} These approaches use an S-shaped popliteal incision,⁸ an L-shaped popliteal incision,^15,89 or a medial incision.^71,90 The senior author recommends a medial incision as described to avoid the popliteal neurovascular structures.

A 7- to 8-cm longitudinal incision, beginning approximately 2 cm proximal to the flexion crease of the knee, is carried distally over the medial head of the gastrocnemius and the posterior border of the semitendinosus tendon (Fig. 21-34). The straight posteromedial incision, compared with an S-popliteal incision, avoids the horizontal popliteal skin crease with less skin retraction necessary and possible wound breakdown.⁸⁹

FIGURE 21-34 Intraoperative photograph of the left knee with the lower extremity in a figure-four position. The longitudinal incision begins approximately 2 cm proximal to the flexion crease of the knee. The incision is carried distally over the medial head of the gastrocnemius and the posterior border of the semitendinosus tendon.

(From Noyes, F. R.; Medvecky, M. J.; Bhargava, M.: Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa. Arthroscopy 19:894–905, 2003.)

Dissection is carried down sharply through the skin and subcutaneous tissues. Care is taken to protect the saphenous nerve posterior to the sartorius muscle and the infrapatellar branches that cross the sartorius superficially. The long saphenous vein and the saphenous branch of the descending genicular artery follow the course of the saphenous nerve and are protected as well. The gracilis and semitendinosus lie deep to the sartorius and are palpated.

Critical Points POSTERIOR CRUCIATE LIGAMENT ARTHROSCOPIC-ASSISTED OPEN TIBIAL INLAY TECHNIQUE: IDENTIFICATION OF FEMORAL PCL ATTACHMENT: VASTUS MEDIALIS OBLIQUUS APPROACH

• Identify PCL femoral attachment, graft location as in all-inside technique.

• Use VMO approach for femoral tunnels with outside-in technique.

• Place guide pin 12 mm proximal to the articular cartilage for both tunnels.

• Start 1 o’clock guide pin just medial to femoral trochlea in an anterior position, begin 4 o’clock tunnel just anterior to femoral epicondyle.

• Alternative technique: use core reamer to harvest bone graft for patella defect. Replace guide pin with core reamer guide pin, visualize during drilling process.

• Chamfer two femoral tunnel entrances into the joint.

• Pass 22-gauge wire through femoral tunnels into the posterior aspect of the knee adjacent to PCL fossa for later graft passage.

PCL, posterior cruciate ligament; VMO, vastus medialis obliquus.

The first key to the approach is to incise the fascia¹⁵⁷ along the posterior border of semitendinosus tendon adjacent to the medial border of the gastrocnemius muscle. The three pes tendons are then retracted anteriorly (taking the saphenous nerve) and the semimembranosus tendon is visualized (Fig. 21-35).

FIGURE 21-35 Surgical exposure of the left knee shows the development of the interval between the semitendinosus (ST) tendon and the gastrocnemius muscle belly. The sartorial fascia is incised along the posterior border of the ST tendon. The forceps is on the ST tendon. During the superficial dissection, care is taken to protect the main trunk as well as superficial branches of the saphenous nerve. The infrapatellar branch of the saphenous nerve is vulnerable as it superficially crosses the sartorius.

(From Noyes, F. R.; Medvecky, M. J.; Bhargava, M.: Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa. Arthroscopy 19:894–905, 2003.)

The second key to the procedure is the dissection between the semimembranosus muscle and the gastrocnemius tendon. Understanding the anatomy of the posteromedial corner of the knee and the semimembranosus is important to obtain good exposure by mobilization of the semimembranosus tendon for the next portion of the dissection. The dissection uses the interval between the medial border of the gastrocnemius and the posterior border of the common semimembranosus tendon. In order to mobilize the semimembranosus medially and improve exposure, the tendon sheath extensions are incised to allow full mobilization of the semimembranosus tendon (Fig. 21-36). Anterior to the semimembranosus, the posterior oblique ligament is partially incised from the attachment to the semimembranosus tendon to improve exposure. These capsular attachments are later repaired at the end of the procedure. With lateral retraction of the medial gastrocnemius, the inferolateral semimembranosus tendon sheath expansion to the popliteus is visualized and dissected from its attachment to the posterior border of the common semimembranosus tendon. In this way, the insertion of tendon directly onto the posteromedial tibia is exposed.

FIGURE 21-36 Surgical exposure shows the popliteus muscle exposure. The gastrocnemius muscle belly is retraced laterally and the pes tendons and the semimembranosus muscle are retracted by an S-shaped retractor away from the popliteal space, exposing the PCL fossa. Caution must be exercised with the lateral retraction of the gastrocnemius muscle because the neurovascular structures are not fully protected and the retractor should not be placed deep to the gastrocnemius muscle belly.

(From Noyes, F. R.; Medvecky, M. J.; Bhargava, M.: Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa. Arthroscopy 19:894–905, 2003.)

The third key is maintaining the posterior exposure and avoiding undue retraction forces on the gastrocnemius and underlying neuromuscular structures. An S-shaped retractor is placed extra-articularly between the semimembranosus tendon and the medial femoral condyle and levered anteriorly, allowing for anterior retraction of the semimembranosus and pes anserinus tendons and muscle bellies. The medial head of the gastrocnemius is carefully retracted laterally with a Richardson retractor, allowing for exposure of the popliteus muscle belly on the posterior tibia. Care must be exercised at this juncture in the procedure, because undue retraction can avulse branches off the popliteal artery.

The neurovascular structures are not visualized and remain medial to the gastrocnemius muscle (medial head). The anterior tibial artery may lie directly on the popliteal muscle over the PCL fossa or pierce the popliteal muscle just distal to the PCL fossa as already described (see Fig. 21-9).

The fourth key to the procedure is the subperiosteal dissection of the popliteus muscle. Care is taken to gently dissect the popliteal muscle superior border in a distal direction to allow better subperiosteal exposure to the posterior tibia and PCL fossa for later placement of the tibial inlay graft. The inferior medial genicular artery and vein are at the superior border of the popliteus muscle and are easily identified and protected during this step, because the dissection is in a subperiosteal plane anterior and deep to the genicular artery.

Identification of Posterior Tibial PCL Attachment for Inlay Procedure

The PCL tibial attachment site is palpated as a midline depression in the proximal tibial metaphysis, between the two tibial condyles. The width of the PCL is approximately 15 mm⁵¹ and the distal extent of the PCL is marked by a small ridge (posterior tibial step-off) that coincides with the proximal border of the popliteus.¹²³

The fifth key to the exposure is to enter the joint proximal and just behind the semimembranosus tendon, avoiding the medial meniscus attachments. The posterior slope of the proximal tibia and the PCL fossa are palpated and the posterior capsule and OPL incised sharply, starting proximal and superior on the lateral aspect of the medial femoral condyle. The posterior portion of the medial femoral condyle is easily palpated. The posterior capsule just lateral to the medial femoral condyle is incised. The joint is entered directly over the inner aspect of the medial femoral condyle to establish from proximal-to-distal a safe plane of dissection (Fig. 21-37; see also Fig. 21-36). The dissection of the capsule is performed in the midline directly over the PCL fossa with care at the joint line to avoid injury to the posterior medial meniscus tibial attachment. This capsular incision is extended distally and connected to the popliteus subperiosteal exposure, which will be closed at the conclusion of the procedure. The entire PCL tibial attachment site is easily identified. The remaining PCL stump is removed.

FIGURE 21-37 Surgical exposure shows the posterior arthrotomy over the inner aspect of the medial femoral condyle. The suture-passing wires are retrieved from within the joint. Care is taken during the arthrotomy to avoid injury to the medial meniscus. The subperiosteal dissection is carried to the lateral ridge of the PCL fossa to allow for creation of the tibial slot at the anatomic PCL attachment site. An S-shaped retractor assists in positioning the ST out of the operative field, allowing for better visualization of the PCL fossa. The creation of the subperiosteal popliteus flap adds an additional layer of protection and provides a safer exposure, because vascular anatomic variations may exist. Two Steinmann pins allow for retraction of the popliteus and gastrocnemius muscle. B, Anatomic specimen shows line of incision into posteromedial capsule and superior to popliteal muscle to expose PCL tibial attachment.

(A, From Noyes, F. R.; Medvecky, M. J.; Bhargava, M.: Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa. Arthroscopy 19:894–905, 2003.)

Critical Points POSTERIOR CRUCIATE LIGAMENT ARTHROSCOPIC-ASSISTED OPEN TIBIAL INLAY TECHNIQUE: IDENTIFICATION OF POSTERIOR TIBIAL POSTERIOR CRUCIATE LIGAMENT ATTACHMENT FOR INLAY PROCEDURE

• Enter joint proximal and just behind semimembranosus tendon, avoiding medial meniscus attachments.

• Use Richardson retractor to retract medial gastrocnemius muscle. Replace with two Steinmann pins placed just lateral and distal to PCL fossa.

• Remove posterior tibial slot for inlay procedure.

• Placement, adjustment of position of PCL graft.

• Guidewires retrieved, strands passed beginning with 1 o’clock strand.

• Graft strands brought out respective femoral tunnels, positions adjusted proximal-distal direction.

• Tibial fixation graft bone with two 4.0 mm cannulated cancellous screws.

PCL, posterior cruciate ligament.

The sixth key to the exposure involves the Richardson retractor, used to retract the medial gastrocnemius muscle, that is replaced with two Steinmann pins placed under direct vision just lateral and distal to the PCL fossa. The pins allow for excellent exposure during the tibial inlay procedure and avoid undue lateral retraction and pressure against the neurovascular structures by the surgical assistant.

The seventh key is the removal of the posterior tibial slot for the inlay procedure. A 10-mm osteotome is used to cut a rectangular slot into the PCL fossa at the proximal tibia. The slot is started 1 cm distal to the normal PCL attachment, which allows for the proximal bone block and collagenous portion of the graft to assume a normal anatomic position and preserve the proximal 15 mm of the PCL fossa. The posterior interspinous tibial bone just proximal to the PCL fossa is preserved to prevent a vertical PCL graft orientation. The rectangular bone block of the graft is placed flush into the inlay, avoiding too deep a slot, which would produce a vertical PCL graft.

The eighth key is the placement and adjustment of the position of the PCL graft. The previously positioned guidewires are retrieved from the posteromedial capsular recess within the joint. The two strands of the sagittally split graft are identified (lateral arm, 1 o’clock tunnel; medial arm, 3 o’clock tunnel) and are passed individually starting with the 1 o’clock graft strand (Fig. 21-38). Care is taken that there is no soft tissue or native PCL fibers so the graft strands lie directly against the posterior tibia PCL fossa in a normal anatomic position.

FIGURE 21-38 Surgical exposure shows placement of the quadriceps tendon autograft. The rectangular bone portion of the graft has been fixated to the proximal tibia with two 4.0-mm partially threaded cancellous screws. The sutures on the medial and lateral graft strands will be pulled intra-articularly with the suture-passing wires. The graft strands lie directly against the posterior tibia re-creating the normal anatomic PCL tibial attachments.

(From Noyes, F. R.; Medvecky, M. J.; Bhargava, M.: Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa. Arthroscopy 19:894–905, 2003.)

The two graft strands are brought out of their respective femoral tunnels, and the position of the overall graft position is adjusted 5 to 10 mm by observing the graft strand in the femoral tunnel (VMO approach). The graft position is adjusted in a proximal-to-distal direction to ensure the collagen graft strands have the appropriate length for the femoral tunnels. In the alternative procedure, when a B-PT-B graft is used (rather than a QT-PB graft), too proximal a placement of the tibia inlay allows the bone plug to protrude out of the femoral tunnel proximally, compromising interference screw fixation. Too distal a placement of the tibial inlay shortens the graft in the femoral tunnels, also compromising femoral graft fixation. Visualization of both strands of the graft with an outside-in femoral tunnel approach allows for proximal-to-distal graft positioning and final fixation.

Tibial fixation of the graft bone is achieved with two 4.0-mm cannulated cancellous screws. The guidewires for the cannulated drill bit are angled distally to avoid intra-articular penetration, especially as the knee is positioned in a flexed position. A lateral radiograph may be taken intraoperatively to confirm the position of the screws. The length of the screws is usually 30 to 35 mm for adequate purchase.

The capsulotomy is closed, the Steinmann pins removed, and the posteromedial capsule incision and oblique popliteal ligament repaired (Fig. 21-39). The tourniquet is deflated and hemostasis verified. Vascular clips are available should the inferior medial genicular artery or other bleeding sources be identified. The subcutaneous tissues and wound are not closed at this stage to allow for any extravasation of fluid during the final arthroscopic portion of the procedure. After graft fixation, the posteromedial wound is closed in a routine fashion.

FIGURE 21-39 Surgical exposure shows the closure of the semimembranosus sheath and posterior arthrotomy. The skin incision is only partially closed at this point to allow for potential fluid extravasation during the final arthroscopic portion of the procedure.

(From Noyes, F. R.; Medvecky, M. J.; Bhargava, M.: Arthroscopically assisted quadriceps double-bundle tibial inlay posterior cruciate ligament reconstruction: an analysis of techniques and a safe operative approach to the popliteal fossa. Arthroscopy 19:894–905, 2003.)

Graft Conditioning, Tensioning, and Fixation

Arthroscopic visualization of the graft confirms proper placement of both strands prior to fixation. The graft tensioning and fixation steps have been previously described in detail in the “All-Inside Technique” section. A staple post is placed proximal to the femoral tunnels. Fixation is accomplished by tying each suture with approximately 10 pounds (44 N) on each graft strand, at 70° to 90° flexion, and 10 pounds (44 N) anterior tibial load to produce a normal medial tibiofemoral step-off, which is confirmed. A soft tissue absorbable interference screw is added for each tunnel (Fig. 21-40). Arthroscopic evaluation of the graft confirms tension, fixation, and return of stability.

FIGURE 21-40 The final tibial and femoral fixation of the QT-PB two-strand graft.

The patella defect is carefully grafted with bone from the core reamer as described. The anteromedial and posterolateral approaches are closed. The knee is carefully padded in a sterile compression dressing. The lower extremity is placed in a soft hinged knee brace locked at 5° flexion, with a 3-inch cotton roll placed behind the proximal calf to prevent posterior sagging of the tibia. The neurovascular status is confirmed to be normal before leaving the operating room.

Critical Points POSTERIOR CRUCIATE LIGAMENT ARTHROSCOPIC-ASSISTED OPEN TIBIAL INLAY TECHNIQUE: GRAFT CONDITIONING, TENSIONING, AND FIXATION

• Arthroscopically confirm proper placement both graft strands.

• Graft conditioning, tension as described for all-inside technique.

• Tie each suture 10 lb (44 N) on each graft strand, 70°–90° flexion, and 10 lb (44 N) anterior tibial load to produce a normal medial tibiofemoral step-off.

• Soft tissue interference screw added each tunnel.

• Arthroscopically confirm tension, fixation, return of stability.

• Graft patellar defect.

• Soft hinged knee brace locked at 5° flexion with a 3-inch cotton roll behind proximal calf.

Critical Points POSTERIOR CRUCIATE LIGAMENT AVULSION FRACTURES

• Treatment based on type and size of the fracture, displacement, comminution, orientation of fragment.

• Small, partial avulsion fractures, negative posterior translation at 90° knee flexion: brace locked full extension, protected motion, partial weight-bearing for 4 wk to allow healing.

• Complete avulsion fractures: surgical repair. Use either arthroscopic or open technique based on experience.

• Large and medium avulsion fractures: arthroscopic approach, cannulated screw fixation.

• PCL tibial avulsions with small bony fragments: open posterior medial tibial approach.

• Peel-off PCL rupture from femoral attachment: repair PCL attachment with sutures passed through 2- to 3-mm drill holes, avoid epiphyseal plate when still open.

• Authors’ preferred technique: arthroscopic-assisted approach, débride PCL femoral attachment, place tunnel at anterior and posterior aspect of PCL footprint. Tendon augmentation of repair through separate 4- to 5-mm femoral and tibial drill holes may be required. Avoid growth plate.

• Graft augmentation for PCL injuries that extend away from femoral attachment, involving proximal one third of PCL fibers.

• Postoperative protocol suture repair maximum protection, early motion by therapist.

PCL, posterior cruciate ligament.

PCL Avulsion Fractures

Avulsion fractures of the PCL are rare, and treatment options depend on the type and size of the fracture, displacement, comminution, and orientation of the fragment.^52,88 These injuries typically occur at the tibial attachment and may encompass either a small area at the posterior region of the attachment or a large area that extends anteriorly and outside of the PCL attachment. Griffith and colleagues⁵² reported that the entire insertion area was avulsed in all 19 skeletally mature patients in their series of PCL avulsion fractures. The avulsion fracture is usually obvious on routine radiographs. Occasionally, a computed tomography scan is required to define the extent of the fracture pattern in major avulsion fractures extending into the joint.^16,52 Clanton and coworkers²⁵ reported on the importance of the diagnosis of ligament injuries in children and noted two PCL avulsions from the femur that underwent open operative reduction and fixation with sutures. Mayer and Micheli⁸⁵ reported on one case of a PCL femoral attachment avulsion associated with posterolateral instability due to a hyperextension injury mechanism. These authors reported that avulsion or peel-off PCL injuries at the femoral site were rare in the literature.

Patients who have small, partial PCL avulsion fractures, with a negative posterior translation test at 90° knee flexion, are kept in a brace locked in full extension and remain partial weight-bearing for 4 weeks to allow healing. The brace is removed for gentle range of motion (avoiding posterior tibial translation) and quadriceps exercises as described in Chapter 23, Rehabilitation of Posterior Cruciate Ligament and Posterolateral Reconstructive Procedures. Overall, the prognosis for healing and PCL function is good to excellent in these cases.¹⁶³

Complete avulsion of the PCL attachment at the tibia and, less frequently, at the femoral attachment^121,127 (peel-off avulsion) with posterior tibial subluxation, is an indication for surgical repair. Numerous authors have reported favorable clinical results with the open reduction and internal fixation of PCL avulsion fractures at the tibial insertion site.^62,88,150 Inoue and associates⁶² reported on 31 patients followed for 2 to 8 years with good results and low side-to-side differences (<5 mm, KT-2000) after surgery. The authors reported that the majority of knees showed mild residual posterior knee displacement (mean, 3.0 mm). Along with the tibial avulsion, an abnormal MRI signal intensity may be observed within the PCL fibers, indicating partial tearing.

A number of arthroscopic techniques have been reported for PCL tibial avulsion injuries.^16,32,69,139 Kim and colleagues⁶⁹ reported the outcome of 14 knees with an avulsion fracture of the PCL at the tibial attachment. The arthroscope was placed through the posteromedial portal and a plastic sheath with waterproof diaphragm passed through the posterolateral portal. The anteromedial portal was used as required. A large bone fragment was fixed by one or two transtibial cannulated screws placed from the anterior tibia after the bony fragment had been reduced and held by pins. Small bony fragments were fixed with multiple sutures through single or double tibial tunnels. The postoperative program involved a long-leg hinged brace locked at full extension for 3 weeks. Range of knee motion was then initiated with the brace locked in full extension for walking. The brace was removed at 8 weeks. The authors reported all avulsion fractures healed. The 12 knees that underwent operative reduction and fixation operation in the acute phase showed only a trace posterior instability with stress radiographs measuring between 1.2 to 3.5 mm of residual posterior displacement at 90° knee flexion. In 2 patients who had delayed surgery, the residual displacement was 3.3 and 4.1 mm.

Shino and coworkers¹³⁹ reported on six knees that had arthroscopic fixation of a PCL tibial bone avulsion. Fixation was achieved with a single cannulated screw or by suture fixation with comminuted injuries. A pull-out button was introduced through the posteromedial portal and the sutures passed through two tibial drill holes and tied at the anterior aspect of the tibia.

In Kim and colleagues’ study,⁶⁹ postoperative arthrofibrosis developed in 3 of 14 knees, which compromised the final result. The authors concluded that PCL avulsion fractures are amendable for fixation by arthroscopic methods. They speculated that an early range of motion program might be beneficial to prevent arthrofibrosis.

The concept of immediate motion is addressed in detail in Chapter 23, Rehabilitation of Posterior Cruciate Ligament and Posterolateral Reconstructive Procedures. The therapist initiates early and protected knee motion within the 1st postoperative week, applying an anteriorly directed load to protect the relatively weak suture fixation. The use of a posterior calf pad and careful positioning in the brace is required for the first 4 postoperative weeks until suitable healing has occurred. Knees with suture or pin fixation have relatively low tensile strength repairs and require expert postoperative rehabilitation.

The surgeon should select either an arthroscopic or an open technique for tibial avulsion fractures based on experience. In general, it is relatively straightforward to use an arthroscopic approach for cannulated screw fixation for large and medium avulsion fractures. For PCL tibial avulsions with small bony fragments that require a combination of sutures and bone fixation, an open posterior tibial approach is favored by the senior author because it provides good exposure and allows for secure fixation.

A peel-off type of PCL rupture from the femoral attachment has been described as a hyperextension knee injury, such as that reported by Mayer and Micheli⁸⁵ in a child while jumping on a trampoline or in patients suffering from trauma from a motor vehicle accident.^25,115 This type of PCL rupture directly at the femoral attachment may occur at the fibrocartilagenous junction with minor associated damage to the bulk of the PCL fibers. The PCL attachment is easily repaired with sutures passed through small drill holes, avoiding the proximal physeal growth plate.

Ross and associates¹²⁷ described an arthroscopic approach for repair of acute femoral peel-off tears. Three No. 2 nonabsorbable sutures are passed through the PCL substance, through a femoral tunnel at the PCL footprint, and tied over the medial cortex. Park and Kim¹¹⁵ reported an arthroscopic technique that used two transfemoral tunnels for the anterior strand and two posterior tunnels for suture repair of the posterior strand. These authors noted that femoral avulsion injuries were exceedingly rare.

The senior authors’ preferred technique for femoral peel-off or proximal PCL repairs is to use an arthroscopic assisted approach in which two or three guide pin tunnels (small diameter for sutures) are placed at the anterior and posterior aspects of the PCL footprint distal to the physis to fan out the PCL fiber attachment.

A VMO-sparing approach is used as previously described and respective suture passers brought into the knee joint. Through a limited medial arthrotomy and under direct visualization using a headlight, the surgeon places multiple nonabsorbable baseball looped sutures at appropriate sites in the PCL fibers to approximate the broad elliptical femoral PCL attachment. The miniarthrotomy has limited morbidity and allows the surgeon to carefully place multiple sutures into the broad PCL fibers. Secure fixation is achieved along with anatomic placement of disrupted PCL fibers.

The decision is made at this point whether a tendon augmentation of the repair through separate femoral and tibial drill holes is required. In such cases, the arthroscopically assisted tendon augmentation drill holes are first placed in the respective tibial and femoral sites, the graft is passed, and the tibiofemoral joint reduced. A nonirradiated tendon allograft is the senior author’s first choice in skeletally immature patients, and the second choice is a doubled semitendinosus autograft.

The sutures in the proximal PCL stump are placed and brought out through anterior and posterior placed femoral drill holes. In children, the physis is not crossed at either the tibial or the femoral site and the augmentation tunnel is 4 to 5 mm in diameter. In most cases of a peel-off fracture, a tendon augmentation is not necessary because the bulk of the PCL fibers can be brought back to the PCL femoral attachment.

In PCL injuries that extend away from the femoral attachment and involve the proximal third of the PCL fibers, an augmentation is favored. The postoperative protocol for a direct suture repair should take into account the low repair tensile strength requiring maximum protection. The knee is maintained in full extension and the therapist assists in gentle range of knee motion for the first 4 weeks postoperatively. Only toe-touch weight-bearing is permitted during this time period. Then, the patient may progress to 50% weight-bearing in the brace locked at full extension. At 6 weeks postoperative, weight-bearing is progressed in the brace. Knee motion is advanced to 0° to 90°. The brace is removed at 8 weeks.

PCL Augmentation Approaches and Techniques

In select knees, an acute tear of the PCL may occur at the proximal third femoral attachment (and not through the midsubstance). A considerable bulk of the PCL attachment still exists and may be repaired to the femoral attachment, as discussed for the peel-off type of tear. In these cases, it is worthwhile to add a graft augmentation to the attachment site, which may be performed in an arthroscopic-assisted manner. A 7- to 8-mm femoral tunnel is placed at the desired site where the PCL fibers require a graft augmentation, usually in the more proximal aspect of the femoral attachment.

Sutures are used to repair the more distal fibers to the femoral attachment as already described. The placement of a 7-mm tibial tunnel must be well chosen and not interfere with the PCL attachment site. The tunnel is placed just medial to the tibial PCL attachment, carefully avoiding the medial and lateral meniscus attachments. A lateral tibial tunnel is not used because PCL fibers attach in part to the posterolateral meniscus tibial attachment. The authors agree with Wang and colleagues¹⁵⁶ and prefer a three- or four-strand semitendinosus-gracilis (STG) autogenous graft, although an allograft may also be considered.^3,63 Suture fixation to a femoral or tibial post and an absorbable interference tibial and femoral screw in adults is required.

In skeletally immature knees, a small-diameter graft may be placed through the distal femoral and proximal epiphysis, avoiding the physeal plate with suture fixation only (no interference screws) as previously described. An augmentation graft has the distinct advantage of maintaining tibiofemoral reduction and preventing posterior tibial subluxation in the early postoperative healing period. As such, the augmentation graft should always be considered when an area of disrupted PCL fibers exists that would benefit from this approach.

In very select knees with a prior PCL rupture and abnormal posterior tibial subluxation, the remaining PCL fibers may appear healed and intact, although with a residual elongation. Rarely, the senior author has performed a distal advancement of the tibial PCL attachment; this is considered only when the MRI shows a normal signal to the PCL fibers and arthroscopic examination also shows a normal-appearing PCL. The operative approach is similar to a tibial inlay procedure, except the native PCL tibial bone attachment is advanced distally the required amount to restore posterior stability. A proximal advancement (recession) at the femoral insertion is avoided owing to the marked influence of the PCL femoral attachment on PCL fiber function previously described.