The effect of elbow position on the range of supination and pronation of the forearm.

A kinematic study was performed to examine the influence of elbow position on the range of supination and pronation of the forearm. The ranges of supination and pronation were measured in 50 volunteers (25 men and 25 women) using a custom-designed jig which constrained unwanted and confounding movements of the limb. Measurements were taken with the elbow in full extension, 45 degrees flexion, 90 degrees flexion and full flexion. The data showed a reciprocal relationship between the range of supination and the range of pronation of the forearm which depended on the degree of elbow flexion. As the elbow is flexed, the maximum angle of supination increases while the maximum angle of pronation decreases (p<0.001). The converse is true as the elbow is extended (p<0.001).