Spontaneous flexor tendon rupture in the palm: the role of a variation of tendon anatomy.

Spontaneous flexor tendon rupture is rare. We report 2 cases that occurred in association with a common flexor digitorum profundus (FDP) tendon to the ring and small fingers. The tendon bifurcated at the midpalmar level and ruptured at the point of bifurcation. To our knowledge this tendon variation has not been reported previously and has not been associated with spontaneous tendon rupture. Both ruptures occurred in the dominant small finger of elderly men in the absence of trauma. We believe that this unusual tendon arrangement represents a potential weak point in the musculotendinous unit. We discuss the role of this anatomic variant in the pathomechanics of tendon rupture.