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Elbow dislocation

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Elbow Dislocation Overview

Elbow dislocations are the second most common major joint dislocation in adults (after the shoulder) and the most common in children [1, 2]. The elbow joint is complex, involving three articulations within one joint capsule [2]:

  • Humeroulnar Joint: Between the trochlea of the humerus and the trochlear notch of the ulna (a hinge joint allowing flexion/extension).
  • Humeroradial Joint: Between the capitellum of the humerus and the head of the radius (allows flexion/extension and forearm rotation).
  • Proximal Radioulnar Joint: Between the head of the radius and the radial notch of the ulna (allows pronation/supination – rotation of the forearm).

The radius and ulna are strongly connected by the annular ligament (encircling the radial head) and the interosseous membrane [2]. Due to these connections, the radius and ulna typically dislocate together relative to the humerus [1].

Posterior Elbow Dislocation: This is the most common type (80-90%) [1, 2]. The typical mechanism is a fall onto an outstretched hand (FOOSH) with the elbow slightly flexed or fully extended [1]. Hyperextension forces the olecranon process of the ulna into the olecranon fossa of the humerus, acting as a fulcrum [1]. This levers the trochlear notch off the trochlea, tearing the anterior capsule and collateral ligaments (medial/ulnar collateral ligament - UCL, and lateral/radial collateral ligament - LCL complex), allowing the radius and ulna to displace posteriorly relative to the humerus [1].

Significant soft tissue injury occurs, including rupture of the joint capsule and collateral ligaments [1]. The medial epicondyle is a common site for avulsion fractures (where the ligament pulls off a piece of bone) associated with UCL injury, potentially leading to significant bleeding (hematoma) [1].

In younger individuals, injuries around the elbow can sometimes be complex fracture-dislocations or epiphyseal separations (growth plate injuries) that might mimic a pure dislocation [1].

If the coronoid process of the ulna remains partially engaged with the trochlea, it's considered a subluxation or incomplete dislocation [1]. In a complete posterior dislocation, the coronoid process is fully displaced posterior to the humerus [1]. Associated fractures, particularly of the radial head or coronoid process, are common and classify the injury as a "complex" elbow dislocation (as opposed to a "simple" dislocation without fracture) [1, 2].

X-ray of the elbow joint. Imaging is crucial for confirming dislocation, direction, and identifying associated fractures [1, 3].

Symptoms of Posterior Elbow Dislocation & Reduction

Symptoms: A posterior elbow dislocation presents with [1, 2]:

  • Severe pain and immediate inability to move the elbow.
  • Obvious deformity, with the forearm appearing shortened.
  • The elbow is typically held in slight flexion (e.g., 40-70 degrees).
  • The olecranon process is markedly prominent posteriorly.
  • A depression or furrow may be visible above the olecranon due to triceps muscle tension.
  • The distal humerus (trochlea/capitellum) may be palpable anteriorly in the antecubital fossa.
  • The radial head is displaced posteriorly along with the ulna and may be palpable posterolaterally.
  • The normal triangular relationship between the olecranon and the medial and lateral epicondyles of the humerus is disrupted. In extension, these three points normally form a straight line; in flexion, they form an isosceles triangle. In a posterior dislocation, the olecranon sits posterior (and often superior) to the line connecting the epicondyles.
  • Attempts at passive flexion are blocked by the coronoid process impinging on the posterior aspect of the humerus.

Reduction: Prompt closed reduction (realignment without surgery) under adequate analgesia and muscle relaxation (procedural sedation or general anesthesia) is essential [1, 2]. Several techniques exist, but the common principles involve [1, 2]:

  1. Applying longitudinal traction to the forearm to disengage the coronoid from the humerus.
  2. Correcting any medial or lateral displacement.
  3. Applying counter-traction to the upper arm.
  4. Gently flexing the elbow while maintaining traction and guiding the olecranon forward over the trochlea.

A common technique involves the physician stabilizing the patient's humerus (e.g., with an assistant or by placing the patient prone with the arm hanging) while applying downward traction to the wrist/forearm and flexing the elbow [1, 2]. A palpable "clunk" often signals successful reduction [1].

Post-reduction, stability is assessed by gently moving the elbow through its range of motion [1, 2]. Neurovascular status must be re-checked [1, 2]. X-rays are obtained to confirm concentric reduction and rule out associated fractures [1, 2]. Simple dislocations are typically immobilized in a splint or brace at around 90 degrees of flexion for a short period (1-3 weeks), followed by early range-of-motion exercises to prevent stiffness [1, 2]. Complex dislocations often require surgical fixation of associated fractures [1, 2].

Even long-standing dislocations (several weeks or months old) can sometimes be reduced closed, but this becomes progressively more difficult [1].

Lateral Elbow Dislocations: These are variations where the forearm displaces posteriorly and also shifts medially or laterally relative to the humerus [1]. They result from varus or valgus forces combined with the posterior dislocation mechanism [1]. Clinical presentation is more complex, with combined posterior and sideways displacement [1]. Reduction follows similar principles, often requiring additional medial or lateral pressure to correct the sideways shift during traction and flexion [1].

Video demonstrating closed reduction of an elbow dislocation, often performed under procedural sedation (like propofol) for patient comfort and muscle relaxation [2].

 

Anterior & Other Elbow Dislocations

Anterior Elbow Dislocation: This type is rare and usually results from a direct blow to the posterior aspect of the flexed elbow, driving the olecranon forward [1]. It is often associated with an olecranon fracture [1]. The forearm appears elongated, and the humeral condyles are prominent posteriorly [1]. Reduction typically involves traction on the flexed forearm with posteriorly directed pressure on the forearm [1].

Divergent Dislocation: Extremely rare, resulting from severe trauma that disrupts the proximal radioulnar joint and interosseous membrane, allowing the humerus to wedge between the radius and ulna [1]. Reduction requires addressing each bone separately [1].

Isolated Ulna Dislocation: Rare; the ulna dislocates (usually posteriorly) while the radial head remains reduced [1]. Presents similarly to a posterior dislocation but with potential varus deformity and intact forearm rotation [1].

Isolated Radial Head Dislocation: This is more common, especially in children (often termed "nursemaid's elbow" - a subluxation reduced easily) [1]. In adults, traumatic isolated radial head dislocation is uncommon without an associated ulna fracture (Monteggia fracture-dislocation) [1]. It can occur from a direct blow or forceful pronation tearing the annular ligament [1]. The dislocation is usually anterior or anterolateral [1].

  • Clinical Signs: Forearm may be held in flexion and pronation [1]. A valgus (outward) angle at the elbow may be present [1]. The radial head is palpable anteriorly or anterolaterally over the capitellum [1]. Forearm rotation is usually painful and limited [1].
  • Reduction: Can be difficult due to instability from ligamentous damage [1]. Often attempted with longitudinal traction, supination of the forearm, and direct pressure over the radial head while extending the elbow [1]. Maintaining reduction can be challenging; immobilization in flexion and supination may be tried [1]. Irreducible or unstable dislocations may require open reduction and annular ligament repair, or occasionally radial head resection in chronic/complex cases [1].
Elbow dislocation with posterolateral displacement of the proximal radius and ulna (lateral X-ray).
Lateral X-ray showing an elbow dislocation with both the radius and ulna displaced posteriorly and slightly laterally relative to the humerus [3].

Differential Diagnosis of Acute Elbow Injury

Condition Key Features / Distinguishing Points Typical Investigations / Findings
Elbow Dislocation (Posterior/Anterior/etc.) Obvious gross deformity, severe pain, inability to move elbow. Olecranon prominence (posterior), shortened forearm. Often FOOSH mechanism. X-ray confirms loss of articulation between humerus and radius/ulna. Careful neurovascular exam crucial. CT often needed post-reduction for associated fractures (radial head, coronoid).
Supracondylar Humerus Fracture Most common elbow fracture in children, less common in adults. Significant swelling, pain, +/- deformity above elbow. High risk of neurovascular injury (median nerve, brachial artery). X-ray shows fracture line through distal humerus above condyles. Relationship between olecranon and epicondyles maintained.
Radial Head/Neck Fracture FOOSH mechanism common. Lateral elbow pain, swelling, tenderness over radial head. Pain with forearm rotation (pronation/supination). May limit extension. X-ray may show fracture line or subtle signs (fat pad sign). CT can delineate complex fractures. Elbow joint usually congruent unless associated dislocation.
Olecranon Fracture Direct blow to posterior elbow or fall onto flexed elbow. Pain, swelling over olecranon. Palpable gap possible. Inability to actively extend elbow against gravity. Lateral X-ray best demonstrates fracture of olecranon process.
Distal Humerus Fracture (Condylar / Epicondylar) Trauma. Significant elbow pain, swelling, inability to move elbow. May have instability or deformity. Medial epicondyle fracture common in pediatric throwing athletes. X-ray shows fracture involving medial or lateral condyle or epicondyle. May involve joint surface.
Monteggia Fracture-Dislocation Fracture of the proximal ulna combined with dislocation of the radial head (usually anterior). Often FOOSH with hyperpronation or direct blow. X-ray shows ulna fracture AND radial head dislocation (radiocapitellar line disrupted). Requires careful assessment of both components.
Severe Sprain / Ligament Rupture (without dislocation) Significant trauma mechanism. Pain, swelling, tenderness over collateral ligaments (medial or lateral). Instability with varus/valgus stress testing. No gross deformity of dislocation. Clinical exam key for stability. X-rays normal or show avulsion. MRI confirms ligament tear grade.

 

References

  1. Skinner HB, McMahon PJ. Current Diagnosis & Treatment in Orthopedics. 5th ed. McGraw Hill; 2014. Chapter 5: Shoulder & Humerus Trauma (Includes Elbow).
  2. Cohen MS, Hastings H 2nd. Acute elbow dislocation: evaluation and management. J Am Acad Orthop Surg. 1998 Jan-Feb;6(1):15-23.
  3. Roberts DM, Khasriya R, Malone-Lee J. Elbow injuries: Dislocations. BMJ Clin Evid. 2011;2011:1111.