The effect of forearm rotation on laxity and stability of the elbow

Objective. The purpose of this study was to quantify the relationship betwe en forearm rotation and valgus/varus laxity of the elbow joint over the ran ge of elbow flexion. Background There is little known about the influence of forearm rotation on the laxity and stability of the elbow joint. The general opinion exists th at forearm rotation does not significantly influence the laxity and stabili ty of the elbow joint. Methods. Nine fresh-frozen cadaver elbows were used. Passive elbow flexion with the forearm in neutral rotation and in 40 degrees and 80 degrees of pr onation and supination was performed under valgus/varus loads: (1) in intac t elbows; (2) after a lateral surgical approach (lateral epicondylar osteot omy of the distal humerus); (3) after release of the anterior bundle of the medial collateral ligament; and (4) after release of the anterior bundle o f the medial collateral ligament plus radial head resection. Valgus/varus e lbow laxity was quantified using an electromagnetic tracking device. Results. There was a statistically significant effect (P < 0.05) of forearm rotation on valgus/varus laxity throughout the range of flexion. The laxit y was always greater in pronation than in supination, regardless of the sur gical approach or the integrity of the anterior bundle of the medial collat eral ligament or radial head. Conclusions. Valgus/varus laxity of the elbow is forearm rotation-dependent . The potential role of this effect should be considered and controlled for in the design of studies examining laxity and stability of the elbow joint .