Posterolateral dislocation of the elbow joint. Relationship to medial instability

Dislocation of the elbow joint is the second most common dislocation in the upper extremity, dislocation of the shoulder being the most common. It has been reported that uncomplicated dislocation of the elbow joint may be associated with a decreased range of motion, degenerative changes in the elbow joint, ectopic calcification, or neurological deficits. As the medial collateral ligament complex can be completely disrupted during dislocation, we evaluated the association between the long-term results of treatment of simple posterolateral dislocation of the elbow and the presence of persistent medial or valgus elbow instability.

Fifty patients who had a mean age of thirty-three years (range, eighteen to fifty-eight years) had closed reduction of a posterolateral dislocation of the elbow without associated fractures. The extremity was immobilized in an above-the-elbow plaster cast for three weeks. After a mean duration of follow-up of nine years (range, six to thirteen years), forty-one patients were evaluated with an interview, a physical examination, and radiographs made while a valgus load was applied to the elbow.

The average score according to the system of The Hospital for Special Surgery was 91 points (range, 49 to 100 points), and thirty-one patients described their elbow function as good or excellent. Twenty-four patients had evidence of medial instability on radiographs made while a valgus load was applied to the elbow. Twenty-one patients had signs of degeneration of the joint, and twenty-five patients had ectopic ossification. Magnetic resonance imaging combined with arthrography was performed for the first twenty patients; eight had evidence of rupture of the medial collateral ligament, seven had generalized degenerative changes of the cartilage, and four had a chondral defect of the capitellum. (The study could not be completed for the remaining patient.) Medial instability on radiographs was correlated with signs of degeneration (p = 0.001), ectopic ossification (p = 0.01), a worse score according to the system of The Hospital for Special Surgery (p = 0.002), and persistent pain (p = 0.04).

Posterolateral dislocation of the elbow joint can lead to persistent valgus instability that is associated with a worse overall clinical and radiographic result.