Transient entrapment neuropathy of the posterior interosseous nerve in violin players. Eleven white male right handed violin players complained of transient muscular deficit of the extensor compartment of the left forearm during and after prolonged playing. This was associated with paraesthesiae and pain. Relief was achieved keeping the wrist and the elbow flexed, with the supinated forearm held by the contralateral hand. An anatomical study showed changes of the relationship of the posterior interosseous nerve with its surrounding structures with pronation and supination of the forearm. On the basis of the clinical features, the anatomical studies and the response to a simple physiotherapeutic regime, it is suggested that prolonged pronation of the forearm may cause transient entrapment of the nerve. 