The Relationship of Wrist Motion to Ulnar Phalangeal Drift in the Rheumatoid Patient

Abnormalities in the cineradiographs and electromyographs of rheumatoid patients with ulnar drift are presented. Those consist of radial deviation of the wrist and a change in the electrical function of the extensor carpi ulnaris. It is suggested that loss of function of this muscle permits the wrist to develop a radially deviated posture which creates increased forces at the ulnar side of the metacarpo-phalangeal flexor tunnels, and persistence of this pattern favours the development of ulnar phalangeal drift.