Posterolateral dislocation of the elbow joint - Relationship to medial instability

Background: Dislocation of the elbow joint is the second most common disloc ation in the upper extremity, dislocation of the shoulder being the most co mmon, It has been reported that uncomplicated dislocation of the elbow join t 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 disl ocation, we evaluated the association between the long-term results of trea tment of simple posterolateral dislocation of the elbow and the presence of persistent medial or valgus elbow instability Methods: Fifty patients who had a mean age of thirty-three years (range, ei ghteen to fifty-eight years) had closed reduction of a posterolateral dislo cation of the elbow without associated fractures. The extremity was immobil ized in an above-the-elbow plaster cast for three weeks. After a mean durat ion of follow-up of nine years (range, six to thirteen years), forty-one pa tients were evaluated with an interview, a physical examination, and radiog raphs made while a valgus load was applied to the elbow. Results: The average score according to the system of The Hospital for Spec ial Surgery was 91 points (range, 49 to 100 points), and thirty-one patient s dec scribed their elbow function as good or excellent, Twenty-four patien ts had evidence of medial instability on radiographs made while a valgus lo ad was applied to the elbow. Twenty-one patients had signs of degeneration of the joint, and twenty-five patients had ectopic ossification. Magnetic r esonance imaging combined with arthrography was performed for the first twe nty patients; eight had evidence of rupture of the medial collateral ligame nt, seven had generalized degenerative changes of the cartilage, and four h ad a chondral defect of the capitellum. (The study could not be completed f or 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). Conclusions: Posterolateral dislocation of the elbow joint can lead to pers istent valgus instability that is associated with a worse overall clinical and radiographic result.