Spontaneous ulnar dislocation of the index, long, ring and small finger extensor tendons at the metacarpophalangeal joints: a case report.

Finger extensor tendon dislocation at the metacarpophalangeal joint is caused by various etiologies, such as trauma, congenital anomaly, or rheumatoid arthritis. When the dislocation occurs with no etiology, this is called spontaneous dislocation. Although spontaneous extensor tendon dislocation in one, two or three fingers has been described, to our knowledge, simultaneous dislocation in four fingers has not been reported. In this paper, we report a spontaneous ulnar dislocation of all the extensor tendons in the index, long, ring, and small fingers. Repair of the radial sagittal bands of the extensor digitorum communis of the middle and ring fingers reduced dislocation of all the extensor tendons in four fingers.