Acute Dislocations

Indications for Open Reduction

Open reduction of an acute dislocation is usually indicated in the following circumstances:

• 1.

  If anatomic, concentric reduction cannot be achieved by gentle, closed techniques with the patient under general anesthesia. Interposed soft tissues or osteochondral fragments may contribute to the irreducibility.

• 2.

  If a stable reduction cannot be maintained. Articular fractures are often unstable and must be reduced and fixed to ensure stability of the reduction.

• 3.

  If careful evaluation before closed reduction reveals normal neurologic function and, after reduction, a definite, complete motor and sensory nerve deficit becomes evident.

• 4.

  If circulatory impairment distal to the injury is well documented before reduction and persists after reduction. Further assessment of the circulation is essential and should include vascular studies.

• 5.

  If ischemia is persistent. Surgical exploration with appropriate management of the vascular injury is indicated.

Ankle

Dislocations of the ankle without fracture of either the medial or lateral malleolus or the anterior or posterior lip of the distal articular surface of the tibia are extremely rare. Usually, any dislocations that do occur are easily reduced by closed methods. Posterior dislocation of the fibula behind the tibia may contribute to difficulty with closed reduction and at times may require open reduction. Ruptures of the deltoid ligament, the anterior tibiotalar ligament, and the anterior and posterior talofibular ligaments occur alone or in combination. Controversy exists over acute ligamentous repair without evidence of fracture. Good-to-excellent results are possible without acute ligamentous repair; however, syndesmosis and mortise widening should be treated operatively if present. (For discussion of acute fractures of the ankle, see Chapter 54 ; of malunited fractures of the ankle, see Chapter 58 ; and of ruptures of the ligaments of the ankle, see Chapter 90 .)

Patella

Acute Dislocations of the Patella

Acute dislocations of the patella are usually 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 until symptoms resolve, then motion and a Palumbo brace are encouraged for 3 to 6 weeks 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 detect any osteochondral fragments. One study demonstrated articular cartilage injury in 94% of patients; 72% had an osteochondral or chondral fracture, and 23% had patellar microfractures.

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 satisfactory only 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. However, one study found only a 31% success rate with nonoperative treatment in patients who were skeletally immature and had trochlear dysplasia.

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 ).

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 ).

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. If the nerve damage is complete, less than 40% of patients will regain dorsiflexion of foot. The majority of patients with incomplete palsy will regain full motor function.

Knee dislocations can usually 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 ).

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, 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 authors 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 that 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 is usually 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.

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 ).

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 are usually 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 lag screw fixation.

Superior dislocation of the proximal tibiofibular joint is also rare and is frequently 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. Immobilization of the knee in slight flexion should also 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.