Meniscus Tears: Diagnosis, Repair Techniques, and Clinical Outcomes

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Chapter 28 Meniscus Tears

Diagnosis, Repair Techniques, and Clinical Outcomes

INDICATIONS

The importance of the menisci in the human knee is well understood and documented. The menisci occupy 60% of the contact area between the tibial and the femoral cartilage surfaces and transmit greater than 50% of joint compression forces. After meniscectomy, the tibiofemoral contact area decreases by approximately 50% and the contact forces increase two- to threefold.2,45,66,71,83,139 Meniscectomy frequently leads to irreparable joint damage, including articular cartilage degeneration, flattening of articular surfaces, and subchondral bone sclerosis. Poor long-term clinical results have been reported by many investigators after partial and total meniscectomy.* For instance, Scheller and coworkers122 followed 75 knees that underwent partial lateral meniscectomy 5 to 15 years postoperatively and noted that 78% had Fairbank’s signs of radiographic deterioration. Rockborn and Messner114 noted a 50% rate of radiographic osteoarthritis in 30 patients who underwent meniscectomy a mean of 13 years postoperatively. Roos and associates119 followed 82 knees that underwent medial meniscectomy and 25 knees that underwent lateral meniscectomy a mean of 21 years postoperatively and reported that nearly one half had advanced radiographic osteoarthritis compared with a control group. These authors reported that the relative risk of developing osteoarthritis was 3.6 after partial meniscectomy and 7.1 after total meniscectomy. Problems do exist in many meniscectomy natural history studies such as including both partial and total meniscectomy in the same cohort; not assessing the effects of patient body weight, activity level, and overall lower limb alignment on the functional result; failure to include weight-bearing posteroanterior (PA) radiographs in the assessment; and lack of a carefully defined control group for comparison. Still, preservation of meniscal tissue and function remains paramount for long-term joint function.

Candidates for meniscal repair are active patients younger than 60 years of age. Trauma is one of the most common etiologies of meniscus tears. For example, meniscus tears occur in 40% to 60% of patients with anterior cruciate ligament (ACL) ruptures.76,98 The majority of these tears extend into the middle third avascular region and are amendable to a meticulous inside-out suture repair. Magnetic resonance imaging (MRI) provides important information regarding the type of meniscus tear and potential for repair to preserve function.44 In knees in which repair is deemed possible, it is important to restrict strenuous activities and athletics until surgery to avoid further damage to the joint and meniscus.

Degenerative meniscus tears are much less frequently repaired, because the meniscus tissue is poor in quality and often fragmented into multiple pieces. Occasionally, MRI will indicate that a repair may be possible, such as in cases of large horizontal tears. Frequently, the symptoms of tibiofemoral pain will diminish over 6 to 12 weeks in degenerative tears in older patients, allowing a conservative approach. In other knees, symptoms of locking episodes and joint swelling are more persistent or severe and require arthroscopic intervention.

Complications and deteriorating results have been reported by others after the use of all-inside meniscus fixation devices72,74,78,87,125,136 which have reduced failure, stiffness, and displacement properties compared with vertical sutures.25,110 The lack of prospective, randomized level I clinical studies precludes definitive recommendations for the various devices currently available.42,78 Therefore, this chapter focuses on suture repair techniques for various types of meniscus tears.

Meniscus repair is frequently performed with concurrent operative procedures such as knee ligament reconstruction. Patients with lower extremity varus or valgus malalignment and associated meniscus tears are especially considered for meniscus repair. The malalignment produces high medial or lateral tibiofemoral compartment loads, and a functional meniscus is required to prevent articular cartilage deterioration.

Meniscus tears are classified according to location, type of tear, and integrity and damage to meniscal tissue and the meniscus attachment sites.123 This classification, along with meticulous arthroscopic inspection of the tear site, allows the surgeon to determine whether a tear is reparable. The meniscus body is divided into thirds: inner, middle, and outer. Tears located at the peripheral attachment sites (meniscofemoral and meniscotibial) are referred to as outer third tears. Single longitudinal tears are usually located in the outer third region or at the peripheral attachments (Fig. 28-1). These tears are classified as red-red because both portions have an internal blood supply and are repaired in all cases with high success rates expected.

Tears located in the middle third region are classified as either red-white or white-white. Red-white tears occur at the junction between the outer and the middle third regions where the vascular supply is present in the outer third portion of the tear. White-white meniscus tears are located in the inner third region where no blood supply is presumed to exist to either portion of the tear. When a repair is performed for these tears, the sutures may provide access to the vascular supply. In addition, the synovial migration of cells on the surface of the meniscus may occur after rasping of the meniscus-synovium border, providing a vascular supply to the repair site.

Repairs of complex tears and tears that extend into the middle third region are evaluated on an individual basis. Tear patterns in this region include single longitudinal, double longitudinal, triple longitudinal, horizontal, radial, and flap. The rationale for repair of these tears is that removal results in essentially a total meniscectomy because a substantial amount of meniscal tissue is resected (Fig. 28-2). This is especially concerning in younger patients in their 2nd to 4th decades of life and in all athletically active individuals. These tears are often reparable with reasonable success rates, as described later in this chapter.

Single meniscal tears occur in a single plane, regardless of location. These include longitudinal, radial, and horizontal tears. These tears are most commonly found in the posterior horn and are usually reparable. Complex tears occur in more than one plane or direction. These include tears in the vertical plane (double or triple longitudinal), in the vertical and horizontal planes, or in the vertical and radial planes (flap tears). Each component of the tear is identified and may or may not be reparable.

The decision for repair includes the evaluation of the meniscus tissue regarding its integrity and absence of traumatic or degenerative changes. The meniscus tissue should appear nearly normal, with no secondary tears or fragmentation that would affect its projected function. This is a qualitative assessment regarding the quality of the tissue being repaired. The meniscus rim should be trimmed of tear fragments. A horizontal tear into the meniscus rim is a negative variable because it is difficult with sutures to fully restore the tear site owing to inner gaps between the horizontal tear arms. This is one indication in which a fibrin clot may provide a benefit. A meniscus that has been displaced in the notch may shorten and contract within 3 to 4 weeks, preventing reduction, and accordingly, early arthroscopy and repair are indicated. More specific recommendations of repair indications and techniques for specific tears are provided later in this chapter.

CONTRAINDICATIONS

Meniscus tears located in the inner third region are not reparable and require débridement. Chronic degenerative tears usually have tear components in multiple planes and are classified as complex. The surgeon must carefully assess the tear pattern and determine the amount and integrity of meniscal tissue that is present. Many of these tears are not reparable (Fig. 28-3). A large flap tear may be reduced and approximated, and if the tissue has adequate integrity, repair is considered in active patients. Chronic degenerative tears in which poor tissue quality is encountered require débridement. The tissue may be thickened or abnormally firm and altered in shape or length. Horizontal tears frequently involve displacement of the meniscus from the joint such that a repair of the horizontal flaps would not result in restoration of meniscus function.

Small longitudinal tears less than 10 mm in length are not repaired. In addition, incomplete radial tears that do not extend into the outer third region are either left alone or treated by minimal débridement of the unstable edges. Radial tears should not be débrided into functional meniscal tissue that would disrupt circumferential hoop fibers and alter meniscus function.

Candidates for meniscus repair must be compliant and willing to follow the postoperative program of rehabilitation, including crutch support for 4 weeks. Those in whom complex tears are repaired must agree to avoid strenuous activities and deep knee flexion for 4 to 6 months; otherwise, the repair site may be disrupted and fail. Patient education is required preoperatively because complex tears that extend into the avascular region may have a 20% to 25% failure rate and require a repeat arthroscopic meniscus débridement procedure. Patient education is important regarding the goals of the procedure and the failure rate. Patients involved in construction work or other demanding occupations may choose not to have a complex or avascular type of repair. A more difficult problem is the request to remove a reparable peripheral (red-red) tear owing to occupational or athletic pursuits. The senior author has declined to perform this type of procedure. The senior author categorizes meniscus tears into three different types. A red-red tear is repaired and, in select small medial tears (15 mm length), an all-inside approach may be considered. However, if there is any associated meniscus tear site damage indicating the need for multiple sutures, an inside-out repair is performed. A red-white tear of either meniscus is repaired with multiple vertical sutures, as described later, with the belief that this procedure offers a firmer internal fixation and chance of healing over two to four all-inside sutures. This procedure is performed in all active patients, except older patients (>50 yr of age) who are sedentary. A complex tear that is located in both red-white and white-white regions may have a success rate of approximately 50%, and the repair of these more difficult tears is usually performed in young patients in an attempt to preserve some meniscal function. In others, a partial meniscectomy is performed.

CLINICAL BIOMECHANICS

Meniscus Function

The menisci provide several vital mechanical functions in the knee joint. They act as a spacer between the femoral condyle and the tibial plateau and, when there are no compressive weight-bearing loads across the joint, limit contact between the articular surfaces. The amount of joint narrowing due strictly to the physical absence of the menisci is in the range of 1 to 2 mm.

Under static-loading conditions, the menisci assume a significant load-bearing function in the tibiofemoral articulation.2,26,45 At least 50% of the compressive load of the knee joint is transmitted through the menisci in 0° of extension, and approximately 85% of the load is transmitted at 90° of flexion.2 The presence of the menisci increases the contact area to 2.5 times the size of a meniscectomized joint. The larger contact area provided by the menisci reduces the average contact stress (force/unit area) acting between the joint surfaces. Removal of as little as 15% to 34% of a meniscus increases contact pressures by more than 350%.124

Lee and colleagues75 evaluated the biomechanical effects of serial meniscectomies in the posterior segment of the medial meniscus. Compared with the intact state, the medial contact area decreased from 20% (after removal of 50% of the posterior segment of the medial meniscus) to 54% (total meniscectomy). Medial contact stress increased from 24% (50% meniscectomy) to 134% (total meniscectomy). Medial peak contact stress increased from 43% (50% meniscectomy) to 136% (total meniscectomy). The peripheral portion of the medial meniscus provides a greater contribution to increasing contact area and decreasing contact stresses than the central portion. Peak contact stresses increase proportionally with the amount of meniscus removed.

Medial meniscectomy performed after sectioning of the ACL results in increased anterior translation at 20° of knee flexion compared with that measured in knees with an intact ACL.77 Thus, the loss of the medial meniscus after an ACL rupture is problematic, especially in varus-angulated knees. In knees with posterior cruciate ligament (PCL) ruptures, the increase in posterior tibial translation allows a change in tibiofemoral contact in which the menisci posterior horns have a reduced weight-bearing function. This is sometimes referred to as a “PCL meniscectomy.” The effect is greater for the medial compartment in which the middle and anterior thirds of the medial meniscus have less weight-bearing function than the lateral meniscus.

The menisci remain in constant congruity to the tibial and femoral articular surfaces throughout knee flexion and extension135,146 and are thus believed to contribute to stability to the knee joint.92 The lateral meniscus provides concavity to the lateral tibiofemoral joint owing to the normal posterior convexity of the lateral tibial condyle, allowing the stabilizing effect of joint weight-bearing forces to reduce lateral compartment anterior and posterior translations.82 Total lateral meniscectomy results in a 45% to 50% decrease in total contact area and a 235% to 335% increase in peak local contact pressure.103

Loss of the medial meniscus results in a smaller, more medial displacement of the center of pressure. Load is subsequently transmitted through the articular cartilage and subchondral bone to the underlying cancellous bone through this more central route, thus stress-shielding the proximal aspects of the medial tibial cortex. The deleterious effects of meniscectomy on tibiofemoral compartment articular cartilage have been demonstrated in multiple experimental studies.65,104,132,145 For these reasons, it is paramount to preserve meniscal function, if possible, in knees with varus osseous malalignment.

In addition, the menisci provide shock absorption to the knee joint during walking and are theorized to assist in overall lubrication of the articular surfaces.92,141

Meniscus Suture Repair Biomechanics

Various suture repair techniques and suture materials have been tested experimentally to determine initial fixation strength and performance under cyclical loading.13,106 Suture techniques have also been compared with several meniscus repair devices.* Post and coworkers106 compared the pull-out strength of vertical mattress, horizontal, and knot-end sutures in a porcine model using either 2-0 Ethibond, 0-polydioxanone sutures (PDS), or 1-PDS suture material. The vertical mattress technique with 1-PDS suture had significantly greater (P < .05) mean load-to-failure values than any other combination (146 ± 17 N). This was followed by the vertical mattress technique with 0-PDS suture material (116 ± 28 N). The vertical mattress technique had significantly greater mean load-to-failure values than the horizontal mattress technique, regardless of suture type (P < .0001). There was no difference in the relative strength between horizontal and knot-end suture techniques.

Asik and coworkers13 compared the failure strengths of vertical, vertical mattress, vertical loop, horizontal mattress, and knot-end suture techniques in a bovine model. Each group consisted of four medial menisci, and 1-Prolene suture material was used in all specimens. The vertically oriented sutures showed significantly higher initial fixation strengths (mean, ∼131 N) compared with the knot-end (64 N; P < .001) and horizontal (98 N; P < .001) techniques. In another study, Asik and Sener12 compared the mean load to failure of a variety of meniscus repair devices with that of horizontal and vertically oriented sutures in a bovine model. The strongest repair method was the vertical sutures with 0 PDS (mean, 104.7 N). The mean failure strengths of all of the devices were lower than both suturing techniques (range, 9.8 N for the Arthrex dart to 51.4 N for the T-Fix device).

Miller and associates88 assessed healing rates and chondral injuries of three all-inside devices in a goat model 6 months after implantation. A 15-mm longitudinal tear was created in the peripheral 25% of the posterior-central horn and then repaired with either two Meniscal Fasteners (Mitek, Ethicon, Westwood, MA), two 10-mm BioStingers (Linvatec, Largo, FL), or two 10-mm Clearfix Meniscal Screws (Mitek). A group of goats that had undergone repair with two vertical mattress sutures for a similar lesion was used for control.89 The authors reported that the suture group had a significantly higher rate of healing (93% completely healed, 7% no healing) than all three of the device groups (P < .01), which ranged from 43% to 54% complete healing and from 0% to 25% no healing. In addition, significant chondral injury was observed in the majority of animals in all three device groups.

Several investigations compared the biomechanical properties of meniscus arrows with those of vertical and horizontal sutures.4,12,16,24,37,110,126,143 Vertical sutures are superior to both horizontal sutures and meniscus arrows in mean load-to-failure values.12,42,143 Dervin and colleagues37 reported that the meniscus arrow had approximately one half the failure strength of vertical sutures (30 N and 58 N, respectively; P < .001). Song and Lee126 found that the maximum tensile strength of the meniscus arrows was significantly lower (38 N) than both vertical (114 N) and horizontal (75 N) sutures (P < .05). Walsh and coworkers143 reported that the meniscus arrow and meniscus staple had significantly lower mean force-at-failure values (44.3 N and 17.8 N, respectively) than vertical suture (73.9 N; P < .005).

Rankin and associates110 used a bovine model to compare vertical sutures, horizontal sutures, meniscus arrows, and T-Fix repairs in which three sutures or devices were used for each repair. Vertical sutures were stronger than all other repair methods and showed the smallest average residual displacement (0.21 mm). The force required to generate 2 mm of tear displacement was greatest for the vertical sutures and least for the arrow (143 N and 43.6 N, respectively; P < .0001). The superior strength of vertical sutures is believed to be due to the perpendicular orientation to the circumferential collagen bundles of the meniscus.110

Becker and colleagues21 compared the biomechanical behavior of several biodegradable implants for meniscus repair with that of vertical and horizontal mattress sutures in response to cyclical loading and load-to-failure testing. Seventy lateral menisci were removed from patients aged 52 to 60 years prior to total knee replacement. One suture or device was used for each repair. The pull-out strength of the vertical and horizontal sutures was superior to those of the implants. Superior stiffness during load-to-failure testing and lower displacement under cyclical loading were found for the vertical sutures compared with horizontal sutures and all implants.

Nyland and associates100 evaluated displacement (repair site gapping) of all-inside vertically or horizontally placed FasT-Fix (Smith & Nephew, Endoscopy Division, Andover, MA) devices to horizontally placed RapidLoc devices (Mitek Surgical Products, Westwood, MA) under cyclical loading conditions in human cadavers (mean age, 65 ± 7.7 yr). Two implants placed 5 mm apart were used for each repair. The vertical FasT-Fix group had significantly less displacement after 500 cycles than the other two groups (P < .01) and greater stiffness.

Meniscus Repair Healing

There are few published experimental studies on the strength of a healing meniscus suture repair (without cell-based therapy or growth factors) subjected to tensile loads. Newman and associates94 measured the mechanical behavior of canine joints after repair of peripheral and radial meniscus tears. Contralateral limbs served as controls. The peripheral tears were repaired with four vertically oriented sutures, and the radial tears were repaired with two horizontally oriented sutures. Thirteen weeks later, the peripheral repairs demonstrated no statistically significant differences between the repaired and the control limb in compressive force-displacement behavior, input energy, and ratio of dissipated to input energy. All of the peripheral repairs healed, with no gapping at the repair site. However, the radial repairs showed significant differences in the structural and material properties compared with the control limb. These repairs healed with 3- to 5-mm-wide fibrovascular scars, and 10 of 17 (59%) specimens failed to refill the gap completely to the inner meniscal rim. The authors concluded that the mechanical function was restored after peripheral repairs, but not after radial repairs in this animal model.

In a rabbit model, Roeddecker and colleagues117 studied tissue strength after repair of longitudinal meniscal lesions located in the central third region. A 3-mm lesion was created and then either left alone, repaired using one suture, or repaired with a fibrin sealant. The contralateral limb was used as a control. After 6 weeks, the mean relative strength of the healing tissues were 26% (suture) and 42.5% (fibrin glue) of the control values. These strength values remained similar after 13 weeks.

CLINICAL EVALUATION

A thorough history includes assessment of the injury mechanism, initial and residual symptoms, and functional limitations. Common injury mechanisms are a sudden twist, change in direction, or deep knee flexion. Meniscus tears are frequently encountered in knees with ACL ruptures. A comprehensive knee examination is performed, which includes assessment of knee motion, patellofemoral indices, tibiofemoral pain and crepitus, muscle strength, ligament subluxation tests, and gait abnormalities.

The presence of tibiofemoral joint line pain on joint palpation is a primary indicator of a meniscus tear. Other clinical signs include pain on forced flexion, obvious meniscal displacement during joint compression and flexion and extension, lack of full extension, and a positive McMurray test.84 All ligament stability tests are performed and compared with the opposite knee joint. MRI may be obtained using a proton-density–weighted, high-resolution, fast-spin-echo sequence107,108 to determine the status of the articular cartilage and menisci. This evaluation is useful in knees with suspected degenerative tears142 and chronic ACL ruptures and to determine whether a meniscus cyst is present. A recent investigation that examined the ability of MRI to predict reparability of longitudinal full-thickness meniscus lesions reported high sensitivity and specificity rates (overall, 94% and 81%, respectively).95

LaPrade and Konowalchuk73 described a figure-four test that attempts to replicate symptoms in patients with tears of the lateral meniscus popliteomeniscal attachments. The patient is placed supine, the knee flexed to approximately 90°, the foot placed over the contralateral knee, and the hip externally rotated. A varus loading at the knee joint increases tensile loading in the damaged posterolateral soft tissue meniscal attachments. The primary symptom from popliteomeniscal tears is lateral compartment pain with activities, especially turning and twisting with sports. MRI is frequently negative. The authors described an open approach to repair the popliteomeniscal attachments. However, these peripheral tears are amendable to an inside-out repair technique, as is described later.

The clinical examination may reveal tenderness upon palpation at the posterolateral aspect of the joint at the anatomic site of the popliteomeniscal attachments. The McMurray test is performed in maximum flexion, progressing from maximum external rotation to internal rotation and then back to external rotation. This test may produce a lateral palpable snapping sensation, representing an anterior subluxation of the posterior horn of the lateral meniscus with maximum internal rotation. The snapping is produced with external rotation as the meniscus returns to a normal position. Of interest, patients with physiologic joint laxity and increases in tibial rotation limits can commonly produce this lateral snapping sign in both knees under examination, which is not painful. Patients with tears of the popliteomeniscal attachments may have a positive snapping sign in only the symptomatic knee, which produces posterolateral joint pain.

Radiographs taken during the initial examination include lateral at 30° of knee flexion, weight-bearing PA at 45° of knee flexion, and patellofemoral axial. Axial lower limb alignment is measured using full standing hip-knee-ankle weight-bearing radiographs in knees that demonstrate varus or valgus alignment.38 Knees that have deficiency of the posterolateral structures may require lateral stress radiographs. Posterior stress radiographs may be used in patients with PCL ruptures.

Patients complete questionnaires and are interviewed to rate symptoms, functional limitations, sports and occupational activity levels, and patient perception of the overall knee condition according to the Cincinnati Knee Rating System.19

INTRAOPERATIVE EVALUATION

All knee ligament subluxation tests should be performed after the induction of anesthesia in both the injured and the contralateral limbs. The amount of increased anterior tibial translation, posterior tibial translation, lateral and medial joint opening, and internal-external tibial rotation should be documented.

A thorough arthroscopic examination is conducted, documenting articular cartilage surface abnormalities.99 A probe inserted from the medial infrapatellar portal is used to tension the meniscus to determine the integrity of the peripheral rim and the anterior and posterior attachments. The probe is placed underneath the meniscus to visualize the entire undersurface (see Fig. 28-2). Flap tears that otherwise may not be evident may be discovered during this examination.

A 30° or 70° arthroscope is used in the anteromedial portal to examine the posteromedial meniscal region. The anteromedial portal is purposely placed immediately adjacent to the medial border of the patellar tendon. The arthroscope sheath with a blunt obturator is passed along the lateral aspect of the medial femoral condyle distal to the PCL attachment into the posteromedial compartment. The meniscal-synovial junction, the peripheral edge of the meniscus, the opening of a synovial cyst, and the posterior articular surface of the medial femoral condyle are inspected. A nerve hook is passed from the anteromedial portal and brought over the top of the meniscus into the posteromedial compartment. The peripheral attachment of the posterior horn of the medial meniscus frequently cannot be completely visualized unless this view is obtained.27

The posterolateral compartment of the knee may be inspected by passing the arthroscope adjacent to the medial aspect of the lateral femoral condyle at the notch, just distal to the ACL femoral attachment.

The meniscus tear pattern is classified, as previously described. When a longitudinal tear in the middle third region is found, a thorough examination of the peripheral margin of the meniscus is required to determine whether a double longitudinal tear exists in the remaining meniscus rim.

The arthroscopic examination in patients with lateral and posterolateral joint pain may not reveal obvious tears of the posterosuperior meniscus attachments. There may be observable tears in the inferior meniscus tissues about the popliteal hiatus and meniscotibial attachments (Fig. 28-4). There is frequently enlargement of the popliteal hiatus and subtle interstitial tearing of the meniscotibial posterior horn attachments that allow the posterior horn to be abnormally elevated and displaced anteriorly into the lateral compartment. These displacement tests of the posterior horn are performed at 60° to 70° of flexion using a figure-four position because the increased joint gap allows a nerve hook to easily displace the posterior horn and demonstrate the abnormal slackness of the attachments. The authors have frequently encountered athletes who have had a prior negative arthroscopic examination and MRI who have demonstrable posterior horn popliteomeniscal attachment tears that require suture repair.

OPERATIVE TECHNIQUE

Patient Preparation

The patient is instructed to use a soap scrub of the operative limb (“toes to groin”) the evening before and morning of surgery. Lower extremity hair is removed by clippers, and not a shaver. Antibiotic infusion is begun one hour prior to surgery. A nonsteroidal anti-inflammatory drug (NSAID) is given to the patient with a sip of water upon arising the morning of surgery (which is continued until the 5th postoperative day unless there are specific contraindications to the medicine). The use of an NSAID and a postoperative firm double-cotton, double-Ace compression dressing for 72 hours (cotton, Ace, cotton, Ace layered dressing) has proved very effective in diminishing soft tissue swelling and is used in all knee surgery cases. A urinary indwelling catheter is not used unless there are specific indications. The patient’s urinary output and total fluids are carefully monitored during the procedure and in the recovery room. The knee skin area is initialized by both the patient and the surgeon before entering the operating room, with a nurse observing the procedure. The identification process is repeated with all operative personnel with a “time-out” before surgery to verify the knee undergoing surgery, procedure, allergies, antibiotic infusion, and special precautions that apply. All personnel provide verbal agreement.

The patient is placed in the supine position on the operating table so that the affected leg is elevated (Fig. 28-5). The foot of the surgical bed is adjusted to allow 90° of knee flexion. A tourniquet and leg holder are used, but the tourniquet is inflated only for the initial exposure. The leg holder is placed at the middle of the thigh, which allows an assistant to open the tibiofemoral compartment under maximum tension for visualization and meniscus surgery. The extremity is draped free to allow easy positioning during surgery. Standard medial and lateral patellar arthroscopic portals, placed directly adjacent to the patellar tendon, are used for the diagnostic arthroscopy. A common mistake is to place the arthroscopic portals too far medially or laterally over the femoral condyles, where instrument passage damages the femoral articular cartilage. The safe area for instrument passage is with the portal just medial and lateral to the patellar tendon with passage into the femoral notch region.

Critical Points OPERATIVE TECHNIQUE

Multiple 2-0 Braided Polyester Nonabsorbable Sutures Used on 10-Inch Straight Cutting Needle

Diagnostic arthroscopy is performed and the meniscus tear analyzed according to its location, type, and size. The meniscus tissue and synovial junction are rasped to stimulate bleeding at the meniscus-synovium border. Loose, unstable meniscus fragments are removed. In bucket-handle tears, the meniscus rim is prepared before the displaced meniscus is reduced because there are often fragments or partial horizontal clefts in the rim preventing close apposition of the meniscus body to the meniscus rim. Once the synovial fringe and meniscal edges are roughened, the meniscus tear is reduced anatomically. The goal is to restore the meniscus to its original size and shape to promote healing and restore its normal hoop stresses and biomechanical properties.

The inside-out meniscus repair technique requires an accessory posteromedial or posterolateral incision. This exposure allows protection of the neurovascular structures during suture retrieval and knot tying. In the authors’ opinion, an outside-in repair does not allow for the meticulous placement of vertical divergent sutures required for a meticulous meniscus repair for complex and avascular repairs, although it may be adequate for a peripheral meniscus repair. The outside-in–directed needle cannot be controlled adequately to position the sutures along the tear site. Rather, the meniscus tear is only approximated, which reduces the healing capabilities and success rates.

Exposure for Medial Meniscus Repair

With the surgeon seated, using a headlight, and the sterile prepared foot in the surgeon’s lap, the knee is flexed to 60° and a 3-cm vertical skin incision is made just posterior to the superficial medial collateral ligament (SMCL; Fig. 28-6). The tourniquet is inflated for the surgical exposure. The incision is centered just below the joint line (one third above, two thirds below) to allow retrieval of sutures. Avoid placing the incision too posterior in order to protect the saphenous vein and nerve. The subcutaneous dissection proceeds from the superior aspect of the wound down to the fascia. Care must be taken in the inferior aspect of the wound to avoid damage to the saphenous vein and nerve. Two retractors are used to provide visualization of the next layer of structures, the crural fascia and sartorius.

The anterior sartorial fascia is incised, avoiding the sartorius muscle. The pes muscle group is retracted posteriorly. The infrapatellar bundles of the saphenous nerve are identified to avoid injury. The retractors are repositioned to expose the posterior capsule and the semimembranosus sheath and tendon attachments. The key step is to incise the sheath overlying the semimembranous tendon. This opens a window to visualize the medial gastrocnemius tendon. Often, a small synovial Baker cyst is encountered in this interval, which is easily excised. The interval between the medial gastrocnemius tendon and the posterior capsule is bluntly dissected. This plane is developed superior to the semimembranosus tendon. This may be difficult because the semimembranosus tendon may be partially adhered to the posterior capsule. In some knees, the oblique popliteal ligament attachment to the semimembranosus tendon is partially incised to allow the tendon to be posteriorly displaced for exposure and suture retrieval.

Blunt dissection with an index finger allows development of a plane between the medial gastrocnemius tendon and the posterior capsule. A Henning retractor or spoon is inserted, allowing safe suture placement and needle retrieval (Fig. 28-7). The anesthesiologist is asked to provide muscle relaxation so that the gastrocnemius and semimembranosus muscles can be retracted. If the exposure is inadequate at this point, an alternative approach is to further dissect the semimembranosus tendon, which is elevated proximally to gain exposure just distal to the tendon. This is a less ideal approach because it is necessary to avoid placing sutures through the semimembranosus tendon just above its tibial attachment site.

Exposure for Lateral Meniscus Repair

The tourniquet is inflated and the surgeon seated using a headlight with the sterile prepared foot in the surgeon’s lap. The knee is flexed to 60° and a 3-cm skin incision is made just behind the fibular collateral ligament (FCL; Fig. 28-8). The incision is centered just below the joint line (one third above, two thirds below) to allow retrieval of sutures. The interval between the biceps tendon insertion and the iliotibial band is identified and incised, staying superior to the biceps short head muscle fibers. The fascia overlying the posterolateral structures and FCL is gently dissected and peeled from superior to the fibular head. This is performed by applying tension with forceps to the incised fascia and using a thin-blade scissors to peel and strip the fascial tissues to the head of the fibula, protecting the FCL. The retractors are positioned between the biceps tendon and the iliotibial band. The deep layer consists of the posterior capsule and the lateral gastrocnemius tendon. The gastrocnemius tendon has a normal proximal attachment to the posterior capsule, making it necessary to gently dissect the tendon with scissors off the posterior capsule at the joint line. The peroneal nerve inferior to the biceps tendon is palpated and protected, but is not dissected.

The surgeon must be careful to remain posterior to the FCL and other posterolateral structures. The key step is to initially enter the space anterior to the lateral gastrocnemius tendon just above the fibular head. This avoids penetrating and opening the posterior capsule. The space between the posterolateral capsule and the lateral gastrocnemius tendon is further developed bluntly with the index finger. A Henning retractor is used to push the neurovascular bundle medially (Fig. 28-9

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