Simple dislocations of the elbow: evaluation and treatment
Section snippets
Anatomy
The elbow is a trochoginglymoid joint with two principle arcs of motion: flexion–extension and pronation–supination. Flexion and extension occur primarily through the ulnohumeral articulation and secondarily through the radiohumeral articulation. Pronation and supination occur through the proximal radioulnar joint and the radiohumeral articulation. The joint is not a true hinge, but rather has an instantaneous center of motion that follows an irregular pattern [1]. Simulated motion studies
Classification
The classification of elbow dislocations may be divided into simple and complex, depending on the absence or presence of fractures of the distal humerus, proximal ulna, or proximal radius. Injuries that include small osseous fragments originating from the epicondyles or the tip of the coronoid that do affect joint stability are considered simple dislocations. Simple dislocations may be described based on the direction of the dislocation, with the location of the radius and ulna described
Epidemiology
The elbow is the second most commonly dislocated joint in adults, after the shoulder, and the most commonly dislocated joint in children [19], [23]. At present, the epidemiologic research regarding the incidence of elbow injuries is limited and old. The literature that is present suggests that elbow dislocations represent approximately 10%–25% of all elbow injuries, with an annual incidence of 6–8 cases per 100,000 people [29], [30], [31]. An epidemiologic study performed in Malmö, Sweden found
Mechanism of injury and pathoanatomy
Posterior dislocations of the elbow have been postulated to occur as a result of a combination of valgus, supination or external rotation of the forearm, and an axial load through the elbow joint. This leads to posterolateral rotation of the forearm unit relative to the humerus and eventual posterior dislocation of the radius and the ulna as the coronoid passes posterior to the trochlea [38], [39], [40]. More recent studies suggest that a combination of varus, external rotation of the forearm,
Clinical evaluation
The assessment of the patient with an acute elbow dislocation should begin with a complete history, focusing on the mechanism of injury and any associated injuries. Questioning should include symptoms of pain, numbness, paresthesias, and weakness. The multiply injured patient should be assessed according to Advanced Trauma Life Support protocols developed by the American College of Surgeons. Special attention should be given to the head injured patient, because management of elbow injuries in
Diagnostic imaging
The initial radiographic evaluation should include plain anteroposterior and lateral radiographs to document the direction of the dislocation and the presence of associated periarticular fractures. Oblique views may be helpful in evaluating periarticular fractures, but usually they can be performed following reduction of the dislocation [21], [43]. CT may be helpful in assessing more complex fracture patterns and generally is not required when evaluating a simple dislocation. CT usually is
Treatment
Treatment of the simple dislocation begins with a reduction of the involved elbow. Reduction requires adequate muscle relaxation and appropriate analgesia. Ideally reduction in the operating room with the use of a general or regional anesthetic and fluoroscopic guidance is favored, because this allows for a controlled reduction and an assessment of stability following reduction. Circumstances often preclude this, however, and a controlled reduction in the emergency department with the use of
Surgical treatment
The indications for surgical treatment in the setting of a simple acute elbow dislocation are limited. Irreducible dislocations are rare and are secondary to entrapped osteochondral fragments or entrapped soft tissue. Subacute or chronic dislocations require open reduction. Elbow dislocations requiring open reduction generally should be accompanied by ligamentous repair or reconstruction to allow for early range of motion of the joint. A reduction that cannot be maintained with less than 60° of
Postreduction management and rehabilitation
As discussed previously, the examination for elbow stability following reduction helps to guide management and rehabilitation. If the elbow is stable through a full range of motion following reduction and the reduction is concentric on postreduction radiographs, the bony architecture of the elbow combined with the stabilizing effect of the surrounding musculature provides sufficient stability to allow for early unprotected range of motion [8], [19], [20]. The reliable patient may be placed in a
Treatment summary
An algorithm for treatment of simple dislocations of the elbow is presented in Fig. 2. An emphasis is placed on early range of motion to attempt to reduce the incidence of long-term contractures. Although the principle of early range of motion is stressed, of greatest importance is the presence of a concentrically reduced elbow. An early range of motion program begun on a subluxed elbow ultimately leads to a poor outcome. The long-term management of a stiff, concentrically reduced elbow is
Complications
Complications occurring with simple dislocations of the elbow include neurovascular injuries, compartment syndrome, articular surface injuries, chronic elbow instability, late contracture, and heterotopic ossification.
Subacute and chronic dislocations
Subacute and chronic complete dislocations are rare in developed countries, whereas subluxations occur more frequently. Such subluxations generally affect the radiocapitellar joint when combined with posterolateral rotatory instability or the ulnohumeral joint when combined with posteromedial rotatory instability. This occurs most commonly in the setting of fracture dislocations, and treatment of these injuries requires the recognition of the pathology contributing to the rotatory subluxation
Summary
Simple dislocations of the elbow or dislocations occurring without an associated fracture are common injuries. Evaluation of these injuries must include an assessment of the entire involved upper extremity and a complete neurovascular examination. Principles of management include a prompt, controlled reduction, a determination of postreduction stability, and an immediate rehabilitation protocol that considers the stability of the joint following reduction. For those joints that are stable
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