Closed rupture of the flexor tendons of the little finger secondary to non-union of fractures of the hook of the hamate

We report six patients with closed flexor tendon rupture affecting the little finger, occurring secondarily to non-union of the hook of the hamate bone. The ununited fragments were separated from the basal part of the hook by more than 1 mm. The fragments were also rounded and showed marginal sclerosis. Non-union was located in the middle part of the hook in three patients, the tip in two, and the base in one. At operation, the fragments were removed in all patients. Five patients were treated by free tendon grafts using three palmaris and two plantaris grafts and one underwent tendon transfer. Postoperative total range of active motion of the little finger averaged 218° (range 185–265°). All patients returned to their original employment. This series would suggest that flexor tendon rupture can occur after fracture of the hook of the hamate bone, even when the ununited fragment is small and/or rounded.