Isolated avulsion of the flexor digitorum superficialis tendon.

Isolated, closed avulsion of the flexor digitorum superficialis tendon at its insertion is thought to be a rare diagnostic entity, with only six cases reported in the literature. However, we have diagnosed and treated 11 such cases, each presenting with a tender palmar mass and loss of active flexor digitorum superficialis function. Some patients had proximal interphalangeal joint contractures. Upon exploration, the retracted superficialis tendon was found to ensnare the profundus tendon at the level of the A1 pulley. Following tenolysis, flexor digitorum superficialis tendon excision, and in selected patients capsulotomies, each patient achieved good functional capacity.