Flexor tendon entrapment of the digits (trigger finger and trigger thumb)

Flexor tendon entrapment of the digits is a disorder characterized by snapping or locking of the thumb or fingers (with or without pain). Most cases are secondary to thickening of the digit's A1 pulley, but other pathogeneses include tendon abnormalities at the level of the carpal tunnel, thickening of other pulleys, and abnormalities of the metacarpal-phalangeal joint. Its historical name, stenosing tenosynovitis of the digits, is inappropriate because histological studies document a lack of inflammation. Flexor tendon entrapment of the digits is a relatively common, uncomplicated, and non-controversial musculotendinous disorder of the distal upper extremity. The purpose of this invited review is to summarize information from the medical literature on aspects of this condition likely to be of interest and relevant to occupational medicine practitioners. Topics covered include normal anatomy and kinesiology, history, clinical observations related to diagnosis, pathology, pathophysiology, clinical observations on etiology, descriptive epidemiology, epidemiological studies, and case management. Models for the pathogenesis of flexor tendon entrapment of the digits are proposed, and opportunities for future research are presented.