Acute dislocations of the patella usually are managed by closed methods (Fig. 60-1). The patella is almost always dislocated laterally, and extension of the flexed knee with pressure applied to the lateral margin of the patella results in reduction. The limb is immobilized in a knee immobilizer for 3 to 6 weeks and then motion is begun to prevent arthrofibrosis and to promote the formation of strong collagen along the lines of stress. Radiographs should be evaluated carefully to ensure that no osteochondral fragments are displaced within the joint. If a hemarthrosis is present, MRI is warranted to check for osteochondral fragments. One study demonstrated articular cartilage injury in 94% of patients; 72% had an osteochondral or chondral fracture, and 23% had patellar microfractures.

FIGURE 60-1 Patellar dislocation. A, Anteroposterior view. B, Sunrise view.

An MRI study by Balcarek et al. identified either a complete or partial tear of the medial patellofemoral ligament in most patients (98%) after an acute lateral patellar dislocation. The femoral origin was most frequently affected (50%), followed by the midsubstance (10%), and patellofemoral origin (10%). More than one site of injury was found in 22%. In their subgroup analysis, patellar height and trochlear facet asymmetry were significantly different on MRI in patients with patellar or femoral origin injury (or both) compared with patients in an age-matched control group, but no significant differences were noted in patients with solely a midsubstance injury. In addition, the tibial tuberosity-trochlear groove distance in the patellar origin injury subgroup was significantly greater compared with the other subgroups (femoral origin, patellar and femoral origin, midsubstance, and control).

Because the sites of injury of the medial patellofemoral ligament may differ, treating the specific pathology is critical. Whereas a direct repair may be adequate for a lesion at the femoral or patellar origin, it may not be for a combined tear. Furthermore, direct repair is only satisfactory if the ligament is otherwise intact. If ligament quality is poor, or there is a combined tear, a reconstruction may be more appropriate.

Sufficient evidence does not exist to advocate surgical intervention for primary patellar dislocations. After a second dislocation there is a much higher dislocation rate (49%), and surgical intervention may be considered.

Good or excellent results have been reported in 75% of nonoperatively treated knees and 66% of operatively treated knees in one study. Recurrent dislocation occurred in 71% of nonoperatively treated knees and in 67% of operatively treated knees. Fifty-two percent of patients had their first redislocation within 2 years after the primary injury. The patient should be warned of the possibility of future episodes of recurrent patellar subluxation or dislocation.

In most patients, the long-term subjective and functional results after acute patellar dislocation are satisfactory. Initial operative repair of the medial structures combined with lateral release has not been shown to improve the long-term outcome, despite the very high rate of recurrent instability. Routine repair of the torn medial stabilizing soft tissues in acute patellar dislocation is not recommended in children or adolescents.

Arthroscopic techniques for the repair of the medial patellar retinaculum after acute patellar dislocations have been described, but we prefer the open method at our institution if repair is indicated (Fig. 60-2).

FIGURE 60-2 Algorithm for guiding the evaluation and management of acute primary patellar dislocation.

(Modified from Mehta VM, Inoue M, Nomura E, Fithian DC: An algorithm guiding the evaluation and treatment of acute primary patellar dislocation, Sports Med Arthrosc Rev 15:78, 2007.)

Intraarticular Dislocations of the Patella

Intraarticular dislocations of the patella are rare and are of two types. The most common type is a horizontal intraarticular dislocation of the patella with detachment of the quadriceps tendon; the articular surface of the patella is directed toward the tibial articular surface (Fig. 60-3). In the other type, the patella also is dislocated horizontally but its inferior pole is detached from the patellar tendon and the articular surface faces proximally. These dislocations frequently are difficult to reduce by closed methods, and open reduction generally is required, along with repair of the extensor mechanism.

FIGURE 60-3 Intraarticular horizontal dislocation of patella. Quadriceps mechanism usually remains intact.

(From Brady TA, Russell D: Interarticular horizontal dislocation of the patella: a case report, J Bone Joint Surg 47A:1393, 1965.)

Knee

Dislocation of the knee has been considered a rare injury, but it seems to have increased in frequency over the years. It has been noted that the incidence might be higher than recognized because many knee dislocations are reduced at the scene of the injury without subsequent accurate reporting of this diagnosis (Fig. 60-4).

FIGURE 60-4 Knee dislocation. A, Lateral dislocation. B, Anterior dislocation.

Knee dislocations are designated as anterior, posterior, medial, lateral, or rotary, according to the displacement of the tibia in relation to the femur. Rotary dislocations are designated further as anteromedial, anterolateral, posteromedial, or posterolateral. Knee dislocations are true orthopaedic emergencies. Reported series have emphasized the extensive ligamentous damage and potential for vascular complications associated with these injuries. Prompt evaluation and early repair of any vascular damage in the injured extremity is universally recommended.

The incidence of vascular injuries in knee dislocations has been reported to range from 0% to 40%. Some centers use ankle-brachial indices to assess for vascular injury, but we recommend an arteriogram if the dislocation required reduction. When there is doubt concerning an injury to the popliteal artery, a thorough evaluation, including arteriography and early surgical exploration, is mandatory. Continued observation in anticipation of improvement often leads to disaster. The amputation rate is approximately 11% if vascular repair is done within 6 hours, and this increases to 86% if repair is delayed beyond this time period.

Nerve injuries occur in 16% to 43% of dislocations of the knee. The peroneal nerve is injured most often, and the prognosis for return of function after injury is guarded; permanent damage often results.

Knee dislocations usually can be reduced satisfactorily by closed methods. After reduction and in the absence of additional complications, aspiration of the hemarthrosis using sterile technique and immobilizing the knee in full extension are satisfactory temporary treatments. The neurocirculatory status should be checked frequently for 5 to 7 days. A large transarticular pin can be placed through the intercondylar notch of the femur into the intercondylar eminence of the tibia to provide immediate stability for knees that redislocate in a splint or after vascular repair (Fig. 60-5). Transarticular pins have been associated with pin track infection and breakage and should be used with caution. We have found a transarticular pin to be useful when the posterior capsule is completely disrupted, preventing concentric reduction in full extension. The pin is left in place for 4 to 6 weeks, and range of motion is begun. A knee-spanning external fixator can be used in open-knee dislocations with extensive soft tissue injury or in unstable knees after vascular repair. When it is certain that the circulation is not impaired, treatment can be selected for repair of the injured ligaments, as discussed in Chapter 45. Closed reduction may be impossible, however, especially when the dislocation is posterolateral. Blocking of reduction by the interposition of the joint capsule and “buttonholing” of the femoral condyle medially through a tear in the capsule have been reported. A torn tibial collateral ligament or pes anserinus tendon also can block reduction. When an irreducible dislocation is encountered, open reduction through a medial approach often is necessary; however, the approach usually depends on the type of dislocation. The entrapping and torn structures are released and repaired, and the postoperative care is the same as for ligamentous injuries (see Chapter 45).

FIGURE 60-5 Radiograph showing transarticular pins. A, Anteroposterior view. B, Lateral view.

In complete knee dislocations, both cruciate ligaments usually are torn. In addition, the lateral or medial collateral ligament usually is completely disrupted. The decision to repair the ligaments surgically is affected by the presence of any other skeletal injuries, vascular deficits, or open wounds. If possible, however, the ligaments should be repaired or reconstructed early because early ligament repair has been shown to have more satisfactory long-term results than cast immobilization alone. If repair is impossible, however, such as in injuries requiring vascular repair or in injuries associated with large, open wounds, satisfactory results can be obtained by nonsurgical management. A long-leg splint is applied and worn for approximately 2 weeks. Range of motion in a brace is then initiated. Patients who are not selected for surgical repair because of age, activity, or other coexistent pathology usually have stiffness rather than instability as a long-term problem.

Several surgeons have advocated early repair of all injured structures in order to obtain satisfactory outcomes. Only fair or poor results can be expected with nonoperative treatment. When open treatment is selected, the surgeon must be prepared to repair structures medially, laterally, anteriorly, and posteriorly as indicated. MRI can be a valuable tool in preoperative planning. Techniques for repair and reconstruction of the ligaments are found in Chapters 45 and 51.

Many dislocations result in avulsions, rather than midsubstance tears, of collateral or cruciate ligaments. This is particularly helpful in cruciate tears because primary repair of these structures is inferior to reconstruction, whereas replacement of avulsed bone and secure fixation can lead to acceptable results. Posterolateral corner injuries are particularly worrisome and should be treated early (2 to 3 weeks) to avoid having to perform less rewarding reconstructive procedures, which become necessary thereafter.

After stabilization of the patient and diligent neurovascular evaluation, we prefer to operate on these injuries within the first 3 weeks depending on which ligaments are involved, as discussed previously. Knees without posterolateral corner involvement can be treated when range of motion of 0 to 90 degrees is restored.

Proximal Tibiofibular Joint

Acute dislocation of the proximal tibiofibular joint is rare (Fig. 60-6). It usually is the result of a twisting trauma and may be seen in association with other injuries to the same extremity. Patients usually present with pain and a prominence in the lateral aspect of the knee. Injuries of the proximal tibiofibular joint frequently are overlooked. Patients with chronic dislocations or subluxation complain of popping and instability, which can be confused with a lateral meniscus injury. The proximal tibiofibular joint can be oblique or horizontal (Fig. 60-7). More motion is possible in horizontal joints, and the relative restriction of motion in oblique joints is presumably the reason why most injuries occur in them.

FIGURE 60-6 A and B, Acute dislocation of proximal tibiofibular joint. C and D, After closed reduction. Note change in position of fibular head in both views.

(From Stewart MJ: Unusual athletic injuries, Instr Course Lect 17:377, 1960.)

FIGURE 60-7 Two basic types of proximal tibiofibular joints according to Ogden.

Ogden classified tibiofibular subluxations and dislocations into four types (Fig. 60-8): subluxation and anterolateral, posteromedial, and superior dislocations. Keogh et al. concluded after a cadaver study that the diagnosis of suspected dislocations of the proximal tibiofibular joint was best determined with an axial CT scan (Fig. 60-9).

FIGURE 60-8 Ogden classification of disruptions of proximal tibiofibular joint.

FIGURE 60-9 Axial CT scan of cadaver knee. A, Anatomical. B, Dislocated anteriorly. C, Dislocated posteriorly.

(From Keogh P, Masterson E, Murphy B, et al: The role of radiography and computed tomography in the diagnosis of acute dislocation of the proximal tibiofibular joint, Br J Radiol 66:108, 1993.)

Subluxation of the proximal tibiofibular joint is a recurring problem and is associated with pain and generalized joint hypermobility. Rarely, peroneal nerve deficits are present. If the symptoms fail to respond to cylinder cast immobilization, resection of the fibular head is recommended. Arthrodesis of the joint is discouraged because of its relationship to ankle motion and the potential for late, painful complaints referable to the ankle.

Anterolateral dislocations (see Fig. 60-6) were the most common proximal tibiofibular dislocations in Ogden’s series. They usually were treated successfully by closed methods.

Posteromedial proximal tibiofibular dislocations are relatively uncommon. These are difficult to reduce and usually are associated with disruptions of the tibiofibular capsular ligaments and the lateral collateral ligament. When the dislocation is acute, open reduction is recommended with repair of the torn ligaments and temporary extraarticular fixation with Kirschner wires.

Superior dislocation of the proximal tibiofibular joint also is rare and frequently is associated with a fracture of the fibula or proximal dislocation of the lateral malleolus. If open reduction is necessary, the leg is immobilized in a long-leg cast after surgery to prevent ankle motion and motion at the proximal joint that can cause loosening of any pin fixation. Immobilization of the knee in slight flexion also should relax the pull of the biceps femoris on the fibular head. Crutches are used until the long cast is removed at 3 weeks. A short-leg walking cast is then applied. The pins are removed 6 weeks after surgery, and progressive exercises are instituted.

Hip

The hip joint is inherently stable, and hip dislocations generally are produced by high-energy trauma. Often they are associated with multiple injuries to different organ systems. Motor vehicle accidents remain the most common mechanism of hip dislocation, followed by falls from a height, industrial accidents, and, more rarely, sports such as football or wrestling. Posterior dislocations occur much more frequently than anterior dislocations and result from a posteriorly directed force to the flexed knee with the hip also in a flexed position. Lesser degrees of hip flexion and increasing amounts of hip abduction with similarly applied force often result in an acetabular fracture. Anterior dislocations are caused by an abduction and external rotation force to the affected limb.

Patients with an isolated posterior hip dislocation present with hip flexion, adduction, internal rotation, and a shortened extremity. Anterior dislocations cause the leg to be held in a position of abduction and external rotation. Although isolated hip dislocations are easily recognized, associated lower extremity injuries may distract the examining physician from an ipsilateral hip dislocation or may alter the classic position of the dislocated hip. As in any orthopaedic injury, careful physical examination is crucial, with particular attention paid to associated sciatic nerve or ipsilateral knee injuries.

Radiographic assessment of patients with a hip dislocation should include an anteroposterior view of the pelvis before reduction and is repeated after reduction, along with a 45-degree oblique Judet view of the pelvis. CT of the pelvis with 3-mm cuts and bone windows also is recommended after reduction to rule out associated femoral head or acetabular fractures and incarcerated intraarticular fragments and to assess joint congruency.

Hip dislocations are classified according to the position of the femoral head in relation to the acetabulum and according to associated fractures of the acetabulum and proximal femur. Posterior dislocations have been classified by Thompson and Epstein into five types: type I, with or without a minor fracture; type II, with a large single fracture of the posterior acetabular rim; type III, with a comminuted fracture of the rim of the acetabulum, with or without a major fragment; type IV, with fracture of the acetabular rim and floor; and type V, with fracture of the femoral head. Types II through IV with significant associated acetabular fractures are discussed in Chapter 56, and femoral head fractures are discussed in Chapter 55

Anterior dislocations also have been classified by Epstein as follows:

FIGURE 60-10 Bilateral obturator dislocations of hip.

The term central dislocation historically referred to a medial position of the femoral head after a fracture involving the medial wall of the acetabulum of varying types. This subtype is not very descriptive and may be more accurately discussed in terms of the underlying acetabular fracture.

A hip dislocation constitutes an orthopaedic emergency because delaying its reduction increases the risk of osteonecrosis of the femoral head. Hougaard and Thomsen recommended reduction within 6 hours of the injury. They reported an osteonecrosis rate of 4.8% if reduction occurred within 6 hours of injury compared with 53% if reduction was delayed for more than 6 hours after injury. When the initial trauma survey has been made, and life-threatening injuries have been stabilized, the dislocated hip takes precedence over any other orthopaedic injury. Closed reduction of the hip initially should be attempted in the emergency department under intravenous sedation or general anesthesia, if readily available. If other injuries require emergency operative intervention, the initial hip reduction can be performed in the operating room.

The following guidelines for treatment refer to hip dislocations without significant associated femoral head or acetabular fractures (Thompson and Epstein type I). Several methods of closed reduction have been used successfully, all of which generally consist of re-creating the injurious deforming force (for posterior dislocations—flexion, adduction, and internal rotation; for anterior dislocations—abduction and external rotation in extension). Traction in line with the affected femur and small amounts of rotation and abduction and adduction complete the reduction. The Allis maneuver is performed for posterior dislocations as previously described with the patient supine, whereas the Stimson maneuver is similarly performed with the patient prone (Fig. 60-11). Other reduction techniques involve levering the affected limb at the ankle over a fulcrum (Figs. 60-12 and 60-13). Regardless of the method chosen, only two or three attempts should be made at closed reduction. Multiple, increasingly forcible attempts at reduction could lead to an iatrogenic femoral head, neck, or shaft fracture or cartilaginous injury to the femoral head or acetabulum.

FIGURE 60-11 A, Allis maneuver. B, Stimson maneuver.

FIGURE 60-12 Lefkowitz maneuver using physician’s knee as a fulcrum for affected limb. Left hand levers the ipsilateral ankle and controls rotation.

FIGURE 60-13 A, “East Baltimore lift” is shown with physician and assistant’s arms as fulcrum and ankle as lever. B, A second assistant stabilizes the pelvis.

Failed closed reduction of the hip can be caused by “buttonholing” of the femoral head through the capsule, inversion of the labrum, or interposition of the piriformis into the acetabulum. Incarcerated bone fragments from the femoral head or acetabulum or displaced, unstable acetabular fractures that cannot completely contain the dislocated femoral head can cause hip incongruity. If closed reduction fails, anteroposterior and Judet views and a CT scan of the pelvis should be obtained quickly to assess the imposing factor. If the hip is reduced incongruently, skeletal traction with the femoral head slightly distracted is necessary to avoid further cartilaginous injury until surgery can be done. If the hip is irreducible by closed means, open reduction of the hip should be done immediately. Associated femoral head or acetabular fractures can wait a few days for definitive treatment.

The hip approach that is used generally is determined by the direction of the dislocation. Posterior dislocations are treated by the posterior Kocher-Langenbeck type of approach. Anterior dislocations can be reduced by the direct anterior approach of Smith-Petersen or by the anterolateral or direct lateral approaches of Watson-Jones and Hardinge. The anterolateral and direct lateral approaches offer better access to the posterior capsule, if necessary, whereas the anterior approach may offer a better view of femoral head fractures.

Open Reduction of Hip Dislocation

Technique 60-4

Regardless of the direction of the dislocation, when the approach has been made, assess the capsule first.

If the femoral head is buttonholed, extend the traumatic capsulotomy in a T-shaped fashion along the acetabular rim, carefully preserving the labrum, if possible.

Inspect the joint for intervening capsule, labrum, piriformis muscle, or bony fragments.

If necessary, retract or distract the hip manually or with skeletal traction applied through a fracture table or femoral distractor for better assessment of the joint.

When the joint has been cleared of debris, reduce the hip joint by releasing the traction.

Repair the capsule along with the labrum.

Close the wound routinely for the chosen approach.

Postoperative Care

Gait training is begun when the patient regains control of the affected limb. Some authors have advocated postoperative traction and protected weight bearing to decrease the incidence of femoral head collapse from osteonecrosis. The benefits of these measures have not been proven. Patients are advised to avoid putting the hip in the position of the dislocation, and hip abductor and flexor strengthening and gentle range-of-motion exercises are initiated. An abduction pillow is useful in the postoperative period in sedated and noncompliant patients with previous posterior dislocation.

Complications

Osteonecrosis has been reported to occur in 4% to 22% of hip dislocations without associated femoral head or acetabular fracture (Fig. 60-14). Time to reduction plays a role in the development of this complication because multiple studies have shown a direct correlation between the time to reduction and the prevalence of osteonecrosis. In the best of circumstances, a percentage of patients develop avascular changes despite prompt reduction of a dislocated hip. Patients with posterior dislocations and multiple injuries are apparently at increased risk for the development of osteonecrosis. Most patients who develop osteonecrosis have symptoms within 2 years of injury, although late cases of osteonecrosis with radiographic changes delayed 5 years have been reported.