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.

FIGURE 60-14 A, Posterior dislocation of hip. B, Osteonecrosis of femoral head 8 months after closed reduction. Note subchondral sclerosis, narrowed joint space, and femoral head collapse.

Osteoarthritis is the most common complication after hip dislocation. Although a percentage results from osteonecrosis, a significant number of patients develop osteoarthritic changes without radiographic signs of osteonecrosis. The radiographic distinction between these two entities can be difficult. Indentation fractures and transchondral fractures of the femoral head larger than 4 mm have been associated with increased risk of osteoarthritis.

Sciatic nerve palsy complicates simple posterior hip dislocation in 13% of patients. No neurological sequelae have been reported after anterior hip dislocation. The peroneal portion of the sciatic nerve is more commonly affected than the tibial branch. The relationship of the peroneal distribution to the piriformis muscle, tethering of the nerve at the sciatic notch and fibular neck, and the overall morphology of the peroneal division are possible explanations for its relatively increased risk. At least partial recovery of nerve function can be expected in approximately two thirds of patients. Significant controversy exists regarding the merits and timing of surgical exploration of the sciatic nerve after hip dislocation if closed reduction has been successfully performed and nerve function does not improve. Tornetta and Mostafavi recommended nerve exploration only if sciatic function was normal before reduction and deteriorated after closed reduction of the hip.

Recurrent instability occurs extremely rarely after hip dislocation without fracture and is caused by capsular or labral defects or capsular laxity. Capsular repair, labral repair, and bone block augmentation have been advocated for the surgical treatment of recurrent hip instability. Soft tissue repair seems warranted initially with the addition of bony augmentation if acceptable stability cannot be shown intraoperatively after capsular or labral pathology has been treated.

Pubic Symphysis and Sacroiliac Joints

Dislocations involving the symphysis pubis and sacroiliac joints occur only with high-energy trauma. Considerable force is required to overcome the complex ligamentous structures that provide stability to the adult pelvis. The relevant anatomy and appropriate diagnostic and treatment algorithms are included in Chapter 56.

Sternoclavicular Joint

Traumatic dislocation of the sternoclavicular joint usually results from an indirect force on the anterior shoulder with the arm abducted. The most frequent of these injuries is the anterior dislocation in which the medial end of the clavicle is displaced anteriorly. Posterior or retrosternal dislocations also occur. The sternoclavicular joint also can be dislocated congenitally and in developmental, degenerative, and inflammatory processes.

When traumatic dislocation is anterior, considerable pain and swelling and a prominent deformity over the dislocated joint occur. The anteriorly displaced clavicle may appear elevated in relation to the sternum or may remain depressed near the first rib, depending on the extent of ligamentous disruption. Acute anterior dislocations usually can be treated by nonoperative methods, but interposition of the joint capsule or the ligaments may cause the dislocation to be irreducible. If the joint remains dislocated, the medial end of the clavicle causes an unsightly prominence, but for sedentary patients little disability is to be expected.

Posterior dislocation of the sternoclavicular joint, as already mentioned, is less common. It can be a much more serious injury than the anterior dislocation, however, because the trachea, esophagus, thoracic duct, or large vessels in the mediastinum may be damaged by the posteriorly displaced medial end of the clavicle. The posteriorly displaced medial end of the clavicle can produce respiratory distress, venous congestion or arterial insufficiency, brachial plexus compression, and myocardial conduction abnormalities. Occasionally, pressure on these structures makes the dislocation a true emergency. Whether the sternoclavicular joint subluxates or dislocates depends on the extent of the injury to the capsular ligaments, the articular disc, the interclavicular ligament, and the costoclavicular (rhomboid) ligament. Rockwood stressed the importance and the frequency of injuries to the physis of the medial end of the clavicle that may appear to be a sternoclavicular dislocation in patients younger than 25 years old. Groh et al. found that early recognition (<10 days) of posterior dislocations improves the probability of accomplishing a closed reduction. When a closed reduction fails, they recommend open reduction. Closed and open reduction both produced similar good or excellent results in 18 of 21 patients.

In addition to the physical examination and anteroposterior radiographs, tomograms and CT scans can be helpful in making a diagnosis. An apical lordotic view of the upper thorax centered over the sternum usually is diagnostic. In this view, the medial end of the clavicle is anterior or posterior to that of the normal clavicle on the opposite side. Additional special views, such as those suggested by Heinig, Hobbs, Kattan, and Rockwood, also are helpful.

For acute anterior sternoclavicular dislocations, Heinig recommended closed reduction after infiltrating the hematoma with a local anesthetic. In this situation, a meticulous sterile technique must be used. With the patient supine and with a large sandbag between the scapulae, traction is applied to the affected extremity, and the arm is abducted and extended while pressure is applied downward over the dislocated end of the clavicle. When the dislocation is reduced, the joint may be unstable, and the decision must be made whether to accept a residual subluxation or perform an open reduction and an internal fixation. In anterior dislocations, the deformity generally is accepted. If later instability is painful, ligament reconstruction (see Chapter 47) or resection of the medial end of the clavicle (see Chapter 61) may be indicated.

If the sternoclavicular dislocation is posterior, the patient is placed supine with a large sandbag between the scapulae. Traction is applied to the affected extremity, and the arm is abducted and extended. The clavicle is grasped with the fingers or a sterile towel clip, and anterior traction is exerted to assist in reduction. If a towel clip is used, sterile preparation of the skin is carried out first. Buckerfield and Castle described a reduction maneuver consisting of traction on the affected arm with the shoulder in adduction while a posteriorly directed force is applied to the shoulder and distal clavicle. Most posterior dislocations are stable when reduced. After reduction, immobilization can be achieved with a figure-of-eight soft dressing, a commercially prepared clavicular strap, or a figure-of-eight plaster dressing for 4 weeks. Activities should be restricted for 6 weeks. If reduction of the posterior dislocation cannot be obtained by closed methods even with the patient under general anesthesia, open reduction is indicated because of the dangers of leaving the joint dislocated. Kennedy has recommended open reduction and ligament reconstruction because of the significant injury to the joint capsule, articular disc, and extraarticular ligaments. If open reduction is necessary, a surgeon with thoracic surgery experience should be consulted.

If open reduction is necessary, an attempt should be made to obtain stable fixation without the use of transarticular pins. Several deaths have been reported that resulted from the migration of Steinmann pins or Kirschner wires into the heart, pulmonary artery, innominate artery, or aorta. Occasionally, a whole pin migrates, or the pin breaks, and parts of it may migrate. Reports suggest that the incidence of significant complications may approach 25% after sternoclavicular procedures. Waters et al. advocated suture stabilization of costoclavicular and sternoclavicular ligaments for unstable reductions. Such considerations imply that surgical treatment should be reserved for irreducible posterior sternoclavicular dislocations and for significantly symptomatic, old, unreduced, or recurrent anterior sternoclavicular dislocations. If open reduction is required, the approach as described for old, unreduced (see Chapter 47) and recurrent (see Chapter 61) sternoclavicular dislocations can be modified.

Acromioclavicular Joint

Etiology and Classification

Injuries to the acromioclavicular joint usually are the result of a force applied downward on the acromion. The most common mechanism of injury is a fall directly onto the dome of the shoulder. The clavicle rests against the first rib, and the rib blocks further downward displacement of the clavicle. As a result, if the clavicle is not fractured, the acromioclavicular and coracoclavicular ligaments are ruptured. Injuries to the other structures in this area may include tears in the clavicular attachments of the deltoid and trapezius muscles (Fig. 60-15); fractures of the acromion, clavicle, and coracoid; disruption of the acromioclavicular fibrocartilage; and fractures of the articular cartilage of the acromioclavicular joint.

FIGURE 60-15 Dislocation of clavicle often causes tears in clavicular attachments of deltoid and trapezius muscles.

The severity of any superior or posterior displacement of the clavicle is determined by the severity of injury to the acromioclavicular and coracoclavicular ligaments, the acromioclavicular joint capsule, and the trapezius and deltoid muscles. In cadaver dissections, Rosenørn and Pedersen found that if the acromioclavicular ligament, the joint capsule, and these muscles were cut, proximal displacement of the clavicle ranged from 0.5 to 1.0 cm. More important, considerable anteroposterior instability also was present when the acromioclavicular ligament and joint capsule were sectioned. If, in addition to these structures, the coracoclavicular ligaments also were divided, the superior clavicular displacement ranged from 1.5 to 2.5 cm. Horn noted the clinical association of tears or avulsions of the deltoid and trapezius muscles with tears of the acromioclavicular and coracoclavicular ligaments.

Although many surgeons still use three grades of severity of separation, Rockwood and others subclassify these injuries further into types I through VI (Fig. 60-16). Type I injuries result from minor strains of the acromioclavicular ligament and joint capsule. The acromioclavicular joint is stable, and pain is minimal. Although radiographs initially may be negative, periosteal calcification at the distal end of the clavicle may be apparent later. More significant forces cause type II, and the acromioclavicular ligament and the joint capsule are ruptured. The coracoclavicular ligaments remain intact. In this instance, the acromioclavicular joint is unstable. This instability, especially in the anteroposterior plane, causes deformity, and on radiographs the lateral end of the clavicle may ride higher than the acromion, usually by less than the thickness of the clavicle even when stress is applied to the joint. Considerable pain and tenderness are present over the acromioclavicular joint, but stress radiographs are necessary to assess the degree of instability after these injuries. Injuries that result from a force sufficient to rupture the acromioclavicular and coracoclavicular ligaments have been considered grade III injuries.

FIGURE 60-16 Rockwood classification of acromioclavicular injuries. Type I: neither acromioclavicular nor coracoclavicular ligaments are disrupted. Type II: acromioclavicular ligament is disrupted, and coracoclavicular ligament is intact. Type III: both ligaments are disrupted. Type IV: ligaments are disrupted, and distal end of clavicle is displaced posteriorly into or through trapezius muscle. Type V: ligaments and muscle attachments are disrupted, and clavicle and acromion are widely separated. Type VI: ligaments are disrupted, and distal clavicle is dislocated inferior to coracoid process and posterior to biceps and coracobrachialis tendons.

Besides types I and II, Rockwood described types III, IV, V, and VI injuries. Type III injuries consist of disruption of the acromioclavicular and coracoclavicular ligaments and the distal clavicular attachment of the deltoid muscle. The distal clavicle is above the acromion by at least the thickness of the clavicle. Traditionally, this elevation of the clavicle has been attributed to the pull of the trapezius muscle; however, Rockwood suggested that the scapula, including the glenohumeral joint, is depressed, rather than the clavicle being elevated, creating the gap between the clavicle and the acromion. In type IV injuries, the same structures are disrupted as in grade III injuries. The distal clavicle is displaced posteriorly into or through the trapezius muscle. In type V injuries, the distal attachments of the deltoid and trapezius to the clavicle are detached from the distal half of the clavicle. The acromioclavicular joint is displaced 100% to 300%, and a gross separation between the clavicle and the acromion is present. Type VI injuries are rare and are caused by extreme abduction that tears the acromioclavicular and coracoclavicular ligaments. The distal clavicle is displaced under the coracoid and behind the conjoined tendons.

Clinical Findings

In addition to the physical findings of pain, swelling, and an unstable acromioclavicular joint with a mobile distal clavicle, radiographs are helpful in assessing the degree of injury. If the acromioclavicular ligament has been torn, and the coracoclavicular ligaments are intact, anteroposterior instability is the usual finding. Widening of the acromioclavicular joint is noted in the anteroposterior projection in these grade II injuries. Further instability in the acromioclavicular joint is detected by suspending 10 to 15 lb (4.5 to 6.8 kg) of weights to both of the patient’s wrists. If possible, the weights should be tied to the wrists to avoid having the patient hold them; this allows the upper extremity muscles to relax completely. With the patient standing erect, anteroposterior radiographs are made of each acromioclavicular joint, and the two sides are compared. In significant subluxations, the lateral end of the clavicle is displaced superiorly, or the scapula and arm are displaced inferiorly, more than one half the thickness of the clavicle. In dislocations, the distal clavicle is displaced a distance that is equal to or more than its thickness (Fig. 60-17).

FIGURE 60-17 Stress views of acromioclavicular dislocation. A, Without weights. B, With weights.

Treatment

Type I injuries are satisfactorily treated nonsurgically. This usually includes application of ice, use of mild analgesics, immobilization with a sling, early range-of-motion exercises, and reinstitution of activities when comfort permits. Most surgeons agree that type II injuries should be treated similarly, unless significant instability is observed. If the distal clavicle is displaced no more than one half of its thickness, strapping, splinting, or immobilization with a sling for 2 to 3 weeks usually is successful. Six weeks usually must pass, however, before heavy lifting or contact sports can be resumed. Treatment of type III injuries has become less controversial in recent years. Isokinetic testing after nonsurgical treatment of acromioclavicular dislocation has revealed that strength and endurance are comparable on the affected and uninjured sides. Most patients have no difficulty with activities of daily living, but athletes occasionally report pain with contact sports and throwing. At this clinic, we generally treat all type III acromioclavicular joint separations nonoperatively initially with late reconstruction if necessary. In types IV, V, and VI injuries, most authors agree that the displacement of the acromioclavicular joint would be too great to accept and that open reduction and internal fixation are indicated.

It has been suggested that conservative treatment fails chiefly because of the interposition of the articular disc, frayed capsular ligaments, and fragments of articular cartilage between the acromion and the clavicle. The disadvantages of nonsurgical treatment by strapping, bracing, or splinting techniques include (1) skin pressure and ulceration, (2) recurrence of deformity, (3) necessity of wearing the sling or brace for 8 weeks, (4) poor patient cooperation, (5) interference with activities of daily living, (6) loss of shoulder and elbow motion (in older patients), (7) soft tissue calcification, (8) late acromioclavicular arthritis, and (9) late muscle atrophy, weakness, and fatigue. The avoidance of a surgical procedure is a major advantage of closed methods, and, when successful, closed techniques usually result in a stable joint and satisfactory function in the shoulder. To prevent possible complications, however, close observation on a regular basis is necessary and complete patient cooperation is essential.

The difficulties and problems associated with surgical methods include (1) infection, (2) anesthetic risk, (3) hematoma formation, (4) scar formation, (5) recurrence of deformity, (6) metal breakage, migration, and loosening,(7) breakage or loosening of sutures, (8) erosion or fracture of the distal clavicle, (9) postoperative pain and limitation of motion, (10) second procedure required for removal of fixation, (11) late acromioclavicular arthritis, and (12) soft tissue calcification (usually insignificant). Surgical treatment permits inspection of the injury to the joint and removal of any fracture fragments or other obstructions to reduction. It also permits an anatomical reduction and secure fixation that usually allows the resumption of shoulder motion earlier than is possible with closed techniques.

Many different procedures have been devised for the surgical treatment of dislocations of the acromioclavicular joint. They can be divided into five major categories: (1) acromioclavicular reduction and fixation; (2) acromioclavicular reduction, coracoclavicular ligament repair, and coracoclavicular fixation; (3) a combination of the first two categories; (4) distal clavicle excision; and (5) muscle transfers.

Acromioclavicular reduction and transarticular wire fixation, usually with smooth or threaded Kirschner wires, has been used. Acromioclavicular reduction with acromioclavicular repair or reconstruction and coracoclavicular fixation with coracoclavicular ligament repair or reconstruction also has been reported. Coracoclavicular fixation with heavy nonabsorbable suture and transfer of the coracoacromial ligament to the distal clavicle resulted in 89% satisfactory results in a study by Weinstein et al. These researchers also found that early repairs were more likely to have more satisfactory results than late reconstructions, and this was statistically significant. The superior acromioclavicular ligament can be repaired directly or can be reconstructed with the coracoacromial ligament or free tendon grafts. The coracoclavicular ligaments also can be repaired directly when they are not too frayed; they have been reconstructed using fascia lata, free tendon grafts, the coracoacromial ligament, and transfer of the tendon of the long head of the biceps.

Coracoclavicular fixation devices depend on an intact coracoid process and have included single and double wire loops, screws, nonabsorbable sutures, metallic and bioabsorbable suture anchors, and bone grafts. Coracoclavicular bone grafting creates an extraarticular acromioclavicular arthrodesis and reportedly results in no significant restriction of shoulder motion. We have had little experience with this procedure.

Resection of the lateral or distal end of the clavicle has been proposed for the treatment of acute and old acromioclavicular dislocations. If the coracoclavicular ligaments are disrupted, they must be repaired or reconstructed; internal fixation is required, either across the acromioclavicular defect or between the coracoid and the clavicle. Dewar and Barrington described transfer of the coracoid to the clavicle to hold the lateral end of the bone in position. This technique can be combined with resection of the lateral end of the clavicle (see Chapter 47).

Our preferred method for treating acromioclavicular joint dislocations is a technique described by Mazzocca et al. It is an anatomic reconstruction of both the conoid and trapezoid ligaments. This procedure alleviates concerns over hardware migration, inadequate acromioclavicular ligaments for repair, and nonanatomic positioning. Distal clavicular resection is performed routinely to correct altered acromioclavicular joint biomechanics. Autologous semitendinosus graft is preferred, and the reconstruction is augmented preferably with suture tape. Biomechanical studies by Mazzocca et al. demonstrated superior fixation using this technique compared with pin fixation or repair. This technique also can be used for unstable distal clavicular fractures through appropriate drill holes in the clavicle.

Any surgical procedure for acromioclavicular dislocation should fulfill three requirements: (1) the acromioclavicular joint must be exposed and débrided; (2) the coracoclavicular and acromioclavicular ligaments must be repaired or reconstructed; and (3) stable reduction of the acromioclavicular joint must be obtained. Procedures that accomplish these three goals, no matter how the joint is fixed, should produce acceptable results.

Most of the procedures that reduce and fix the acromioclavicular joint should be reserved for patients younger than 45 years old. DePalma’s anatomical dissections and studies suggest that early degenerative changes are developing in the acromioclavicular joint by the third decade, and that significant changes are present by the fourth decade. Although procedures in which the distal clavicle is excised can be used satisfactorily in young patients, older patients with painful, disabling, old acromioclavicular dislocations with degenerative changes should especially be considered as candidates for such a procedure. Various arthroscopic techniques also have been described for acromioclavicular joint fixation, showing fair-to-good results at short-term follow-up. We have limited experience with the arthroscopic treatment of acromioclavicular joint injuries and prefer an open procedure. The treatment of old acromioclavicular dislocations is discussed in Chapter 61.

Anatomic Reconstruction of the Conoid and Trapezoid Ligaments

Technique 60-5

(MAZZOCCA ET AL.)

Make a curvilinear incision 3.5 cm from the distal clavicle in the lines of Langer to the tip of the coracoid (Fig. 60-18A).

Raise full-thickness flaps anteriorly and posteriorly on the clavicle, skeletonizing the clavicle.

Resect the last 10 mm of the distal clavicle, beveling the inferior bone.

Dissect the coracoid posterior to the deltoid. Once the coracoid is exposed, create a tunnel under the coracoid with a right-angle clamp to ensure easy graft passage.

Drill the first tunnel 45 mm from the distal clavicle (35 mm if distal clavicular resection has already been performed) using an appropriate steel reamer. It should be positioned slightly posterior to re-create normal conoid position (see Fig. 60-18A).

Drill the second tunnel 15 mm lateral to the first tunnel slightly anteriorly to re-create trapezoid position (see Fig. 60-18A).

Pass the lateral limb of the graft with suture through the first (posterior) tunnel, cross it posteriorly so that it will ultimately be a figure-of-eight. Then feed the medial limb of the graft through the anterior tunnel. Do not cross the suture, but pass it directly so that it will be a circle (Fig. 60-18B).

Secure the graft with a soft tissue interference screw in the posterior or anterior tunnel, bringing the suture up through the cannulated screw.

With upper displacement of the scapulohumeral complex, slightly overreduce the acromioclavicular joint. After assessment of correct screw placement, place a second screw in the final bone tunnel.

Confirm the reduction with C-arm Zanca view. Tie the suture (Fig. 60-19).

Route the remaining lateral limb of the tendon graft, and suture it to the acromion as in an acromioclavicular ligament reconstruction (Fig. 60-20).

Close the deltotrapezial interval securely, and close the skin with absorbable monofilament suture (Fig. 60-21).

FIGURE 60-18 Mazzocca anatomic coracoclavicular reconstruction. A, Incision and tunnel placement. B, Graft passage. SEE TECHNIQUE 60-5.

FIGURE 60-19 Mazzocca anatomic coracoclavicular reconstruction. Interference screw fixation of graft to clavicle. SEE TECHNIQUE 60-5.

FIGURE 60-20 Mazzocca anatomic coracoclavicular reconstruction. Final placement of grafts. SEE TECHNIQUE 60-5.

FIGURE 60-21 A, Grade V acromioclavicular dislocation. B, After Mazzoca anatomical reconstruction with Mumford procedure.

Postoperative Care

A brace is worn for 6 weeks, removed only for active-assisted and pendulum exercises. Strengthening begins at 12 weeks, and return to sports is in 6 months

Coracoclavicular Suture Fixation

Technique 60-6

Make a curved incision to expose the acromioclavicular joint, the distal end of the clavicle, and the coracoid process.

Expose the acromioclavicular joint, and remove any loose fragments or other debris.

Place mattress sutures in the ruptured coracoclavicular ligaments, but do not tie them.

Using a -inch drill bit, make two holes in the clavicle above the coracoid in the anteroposterior plane.

Pass a No. 5 nonabsorbable suture beneath the base of the coracoid and superiorly through the two holes in the clavicle. With the joint reduced, tie the sutures. The entire clavicle is not encircled by the sutures because motion might cause the suture to erode through the entire bone.

At this point, if the surgeon is concerned about anteroposterior instability, a small Kirschner wire can be passed across the acromioclavicular joint and bent on its end. Tie the sutures already placed in the coracoclavicular ligaments.

Repair the acromioclavicular joint capsule, and reattach the origins of the deltoid and trapezius muscles to the distal clavicle.

Apply a Velpeau dressing or sling-and-swath bandage.

Postoperative Care

At 2 weeks, the Velpeau dressing and the sutures are removed. Active shoulder exercises are begun. At 8 weeks, any Kirschner wire that has been used is removed with the patient under local anesthesia.

Distal Clavicular Excision

Technique 60-7

(STEWART)

Expose the acromioclavicular joint, the lateral end of the clavicle, and the coracoid through an anterior curved incision.

Incise the capsule and the superior acromioclavicular ligament in line with the clavicle to allow subperiosteal exposure of the clavicle and subsequent capsular and ligamentous repair.

Resect subperiosteally the lateral 1 cm of the clavicle; use a bone-cutting forceps or an oscillating saw to osteotomize the bone obliquely in an inferolateral direction (Fig. 60-22).

Remove the superior subcutaneous edge of the remaining end of the bone with a file.

Place mattress sutures in the ruptured coracoclavicular ligaments, but do not tie them.

Insert two Kirschner wires the size of a guidewire about 2 cm apart through the lateral border of the acromion so that they enter the middle of the articular facet of the acromion. To accomplish this more easily, pass the wires retrograde from the acromial articular surface through the acromion and out through the skin.

While the lateral end of the clavicle is held in normal position, advance the wires into the clavicle for 2.5 to 4.0 cm. As described for the modified Phemister technique, check the position of the wires by radiographs, bend them, and cut them off beneath the skin.

As an alternative, the method of coracoclavicular fixation described by Weaver and Dunn can be used.

Hold the clavicle in the reduced position relative to the acromion and coracoid.

Apply traction to the coracoacromial ligament to determine the proper length of ligament necessary to maintain the reduction. Excise the excess ligament, and place a mattress suture of a No. 1 nonabsorbable material in the ligament, leaving the suture ends free.

Drill two small holes in the superior cortex of the clavicle, and pass a suture end through each (Fig. 60-23A).

Hold the clavicle in the reduced position, and pull on the suture to bring the coracoacromial ligament into the medullary canal of the clavicle (Fig. 60-23B). Tie the suture while the reduction is maintained.

Repair the capsule and ligament of the acromioclavicular joint, and tie the sutures previously placed in the coracoclavicular ligaments.

FIGURE 60-22 Stewart technique for acute dislocation of acromioclavicular joint. A, Soon after injury. B, Six weeks after surgery. C, Three months after surgery. SEE TECHNIQUE 60-7.

FIGURE 60-23 Technique of Weaver and Dunn for acromioclavicular separations. SEE TECHNIQUE 60-7.

Postoperative Care

A sling is worn for 1 week while gentle active circumduction exercises are performed. At 2 weeks, the sutures are removed and the exercises are increased. Heavy lifting is avoided for at least 4 weeks, and then normal activities can be resumed, but contact sports should be avoided for at least 8 weeks.

Shoulder

Uncomplicated dislocations of the shoulder rarely require open reduction. Some acute anterior dislocations of the shoulder are irreducible because of interposition of the long head of the biceps tendon, greater tuberosity, or fracture fragments of the glenoid. Fracture-dislocations of the shoulder are discussed in Chapter 57. Rotator cuff tears that require repair also have been reported with shoulder dislocation (see Chapter 46).

The biomechanics and pathoanatomy seen with recurrent dislocations are discussed in Chapter 47. In an effort to determine which shoulders are prone to recurrent dislocation, Baker et al. identified intraarticular lesions of the shoulder and classified these into three groups. Group 1 (6 patients) had capsular tears with no labral lesions. The shoulders were stable on examination under anesthesia, and hemorrhage was present in the inferior capsule between the middle and inferior glenohumeral ligaments. No Hill-Sachs lesions were identified. Group 2 (11 patients) had subluxable shoulders on examination under anesthesia with partial detachment of the labrum from the glenoid rim and the inferior glenohumeral ligament attachment to the biceps insertion. Hill-Sachs lesions were identified in this group. Group 3 (28 shoulders) showed gross instability on examination under anesthesia and complete disruption of the inferior glenohumeral ligament insertion anteriorly. Hill-Sachs lesions also were seen.

Recurrent instability in young patients has been reported in up to 90% of patients treated nonoperatively. Up to 12% recurrence has been reported in operatively treated shoulders. Arthroscopic stabilization has been recommended in active young patients with no history of subluxation or impingement who may otherwise have recurrent dislocations after acute traumatic dislocation. We currently favor initial nonoperative management for first-time dislocations but consider arthroscopic stabilization procedures an appropriate alternative in selected patients (see Chapter 52 for arthroscopic shoulder stabilization techniques).

Elbow

The elbow is the second most common joint dislocated in adults. Approximately 20% of dislocations are associated with fractures. Acute dislocation of the elbow is almost always reducible by closed methods, and most are stable after reduction. Open reduction may be required if fracture fragments in a fracture-dislocation block closed reduction. Late elbow instability and stiffness are rare after simple dislocations.

Treatment principles of simple dislocations include reduction of the joint and early motion. One study found that patients with unstable elbow joints treated nonoperatively had fewer symptoms than patients treated with ligament repair. Unprotected flexion and extension exercises within 2 weeks of dislocation has been recommended. Burra and Andrews recommended operative treatment when throwing movements are required by athletes.

Dislocation of the Radial Head

If dislocation of the radial head occurs without dislocation of the humeroulnar joint, the radial head is almost always displaced anteriorly and can be easily reduced manually. Because the annular ligament has been ruptured or displaced, the pull of the biceps muscle often causes the dislocation to recur, and unless the radial head remains reduced, it would limit flexion of the joint. Consequently, open reduction and repair or reconstruction of the annular ligament is indicated (1) when the dislocation recurs after closed reduction and immobilization of the elbow in more than 90 degrees of flexion; (2) when it has gone untreated for 2 to 4 weeks; or (3) when it is irreducible by closed means, usually because the radial head is trapped by interposed soft tissues. When the dislocation has gone untreated for more than 4 or 5 weeks in an adult, the radial head should be excised (see Chapter 57).

Open Reduction of Radial Head Dislocation

Technique 60-8

Make an incision over the posterior aspect of the radial head, expose the head, and identify the annular ligament (Fig. 60-24).

Reduce the dislocation, and, if possible, repair the ligament and disrupted capsule with fine interrupted sutures.

If repair is impossible, take a fascial graft 1.3 cm wide × 10 cm long from the outer aspect of the thigh (or from the deep fascia on the dorsal aspect of the forearm, as described in Chapter 57).

Expose the posterior surface of the ulna through a second incision 5.0 cm long, and drill a hole transversely through the bone 1.3 cm distal to the level of the radial head.

Pass the strip of fascia lata through this hole and around the radial neck, and suture its ends together without tension, creating a new annular ligament.

FIGURE 60-24 Dislocation of radial head. A, Annular ligament has been ruptured. Often, this ligament can be sutured satisfactorily. B, If necessary, annular ligament can be reconstructed with strip of fascia lata. Inset, Reconstruction has been completed. SEE TECHNIQUE 60-8.

Postoperative Care

With the arm in a splint or a cast, the elbow is immobilized at 90 degrees of flexion with the forearm in neutral rotation for 2 to 3 weeks. Gentle active motion and especially rehabilitation of the muscles are begun. The elbow must not be manipulated, and motion must not be passively forced in any attempt to restore function. After motion and strength have been actively restored, the head may become slightly displaced, but, if so, it does not interfere significantly with function.

Dislocation of Radial Head and Fracture of Proximal Third of Ulna (monteggia Fracture)

The treatment of a Monteggia fracture is described in Chapters 36 and 57.

Fracture-Dislocation of Elbow with Severe Damage of Soft Structures

Complex elbow dislocations with associated fractures may require surgical intervention to obtain joint stability. This typically includes ligament or fracture repair. A fracture-dislocation of the adult elbow in which the soft structures have been severely damaged should not be treated by closed methods but by débridement and repair. This operation occasionally is indicated if the radial head and the coronoid process of the ulna have been fractured and severe damage to the soft tissues is evident. Large periarticular fractures have been shown to affect functional results adversely. A fractured coronoid process strongly suggests that the elbow had become at least partially dislocated at the time of the injury. At surgery, the brachialis muscle may be found to be torn, the anterior part of the capsule of the elbow joint to be avulsed, and either one or both collateral ligaments to be ruptured. If the injuries of the soft structures are repaired at the same time as the injuries to the bone, the return of function can be hastened, the final range of motion can be improved, and the potential for myositis ossificans around the elbow can be reduced. This open reduction is only for fracture-dislocations of the elbow with severe damage (see Chapter 57 for ligament repair techniques). In a severe fracture-dislocation of the elbow, it is important to assess the integrity of the distal radioulnar joint.

Distal Radioulnar Joint

An injury to the distal radioulnar joint can occur in association with almost any fracture of the forearm or as an isolated injury. A dislocation of this joint may be simple or complex. Failure to recognize a simple dislocation of the distal radioulnar joint associated with a fracture of the forearm may result in inappropriate or inadequate immobilization of the joint after fixation of the fracture. Consequently, the injured triangular fibrocartilage complex may not heal, leading to recurrent postoperative instability. Failure to diagnose and treat a complex distal radioulnar joint dislocation can lead to chronic persistent subluxation or dislocation and to symptomatic osteoarthrosis.

The chief function of the distal radioulnar joint is to stabilize the forearm during pronation and supination as the radius rotates on the distal end of the ulna. The distal ulna is completely covered by cartilage and articulates with the ulnar notch of the radius except on its ulnar side. The distal radioulnar joint is stabilized by the following structures: the ulnar collateral ligament, which is attached to the tip of the ulnar styloid and to the pisiform and triquetrum; the articular disc, which is attached to the base of the ulnar styloid and to the margin of the ulnar notch of the radius; the anterior and posterior radioulnar ligaments, which are parts of the joint capsule; and the pronator quadratus muscle, which spans the volar surface of the distal radius and ulna and the interosseous space. For the distal radioulnar joint to become dislocated, some or all of these structures must be injured.

A distal radioulnar dislocation can be dorsal or volar (Fig. 60-25). If the dislocation is with the ulna in the dorsal position, reduction usually is accomplished by supination of the forearm with pressure on the distal ulna. If the dislocation is with the ulna in the volar position, pronation of the forearm usually is successful in reducing the dislocation. An excellent result usually can be expected if it is reduced early and immobilized for 1 month in plaster. If the dislocation is less than 2 months old and cannot be reduced closed, open reduction with exposure and repair of the triangular fibrocartilage is advised. If the dislocation is reduced surgically after more than 2 months, consideration should be given to excision of the distal ulna and distal ligament reconstruction. According to Milch, rupture of the distal radioulnar ligaments usually causes diastasis of the distal radioulnar joint. He stated that this separation can be seen on radiographs and is a pathognomonic sign that the ligaments have been ruptured and should be repaired. Irreducible dislocations of the distal radioulnar joint have been described In most patients, the extensor carpi ulnaris was entrapped in the joint and prevented closed reduction. A dorsal approach was used to free the extensor carpi ulnaris, and repair of the triangular fibrocartilage or transosseous pinning was used to stabilize the joint.