ELBOW VALGUS STRESS RADIOGRAPHY IN AN UNINJURED POPULATION

Valgus instability of the elbow joint is a clinical diagnosis. However , many authors describe valgus stress radiographs as an aid in making this diagnosis. We studied valgus stress radiographs of 20 men (40 elb ows) and 20 women (40 elbows), none with a history of elbow trauma or instability. The medial ulnohumeral distance was measured with no stre ss, valgus stress by gravity, and an applied valgus stress of 25 N (ap proximately 5 pounds). Measurements were made with the elbow positione d in extension and in 30 degrees of flexion. The increase in medial ul nohumeral gapping with either gravity or 5 pounds of stress was statis tically significant at both extension and 30 degrees of flexion compar ed with the unstressed condition. The difference in ulnohumeral gappin g between gravity stress and 5 pounds of valgus stress in extension an d in 30 degrees of flexion was also significant. We found no differenc es with regard to hand dominance or sex. We conclude that uninjured el bows have significant medial ulnohumeral gapping on valgus stress radi ography, Although this is an important tool in diagnosing valgus insta bility of the elbow, it may yield a false-positive assessment of valgu s instability. Valgus stress radiographs comparing contralateral elbow s may reduce the false-positive rate since there appears to be no sign ificant difference in medial ulnohumeral gapping between the two elbow s.