Review Question - QID 216877

The patient has a posterior elbow dislocation, of which the lateral ligamentous complex is the first structure to fail. Of the lateral ligaments, the lateral ulnar collateral is the most important for stability requiring surgical repair.

Posterior elbow dislocations can be simple or complex (associated with fractures). Most simple elbow dislocations can be treated with closed reduction, brief period of immobilization (5-10 days), and then gradual range of motion, ensuring the elbow is not brought into extremes of motion initially to avoid recurrent instability. However, cases with persistent instability, irreducible dislocations, and complex dislocations require surgical treatment. The lateral collateral ligamentous complex is the first ligamentous structure to fail, with progression then medially. The medial collateral ligaments are the last to fail. Of the lateral collateral ligaments, the lateral ulnar collateral ligament is the most important for elbow stability and can require surgical repair or reconstruction if the elbow remains unstable. Most often, the ligament sustains a proximal avulsion injury.

O'Driscoll, et al. performed a cadaveric study on 13 specimens examining the spectrum of elbow instability. They reported dislocation is the final step in three phases of instability progressing in a lateral to medial direction. They concluded the elbow should be reduced in supination and immobilized in pronation.

McKee, et al. performed a retrospective study of 62 cases treated surgically for elbow instability and classified the degree of lateral soft-tissue injury. They described the injury to the lateral collateral ligament as proximal avulsion in 32 cases, bony avulsion from lateral epicondyle in 5 cases, midsubstance rupture in 18 cases, ulnar avulsion in 3 cases, ulnar bony avulsion in 1 case, and combined injury mechanism in 3 cases. They concluded repair of the lateral ligamentous complex is an important part of the surgical treatment of elbow instability.

Figures A and B are the AP and lateral radiographs of the left elbow demonstrating a posterior elbow dislocation.

Incorrect answers
Answer 1: The radial collateral ligament can often be injured with posterior elbow dislocations. However, this is not as essential to elbow stability as the lateral ulnar collateral ligament.
Answers 3 and 4: The medial collateral ligament is the last ligament to be injured depending on the degree of energy. This does not require surgical repair in all cases.
Answer 5: The accessory collateral ligament does not supply significant elbow stability requiring surgical repair.