Rupture of small finger flexor tendons secondary to asymptomatic nonunion of the hamate hook

The incidence of fractures of the hamate hook (hamulus) has been reported to be between 2% and 4% of all carpal fractures. Untreated hamulus nonunion can cause attritional rupture of the ulnar digits' flexor digitorum profundum tendons. Rupture of flexor tendons due to nonunion of the hook of the hamate is an uncommon injury. Most surgeons treat the tendon lesion by a graft, transfer of the superficial flexor of the ring finger, or terminolateral suture of the distal stump of the deep flexor tendon of the little finger to the deep flexor tendon of the ring finger. This article reports a case of a 52-year-old right-handed man who presented with weakness of grip and loss of active flexion of both distal and proximal interphalangeal joints of the right small finger lasting 2 weeks due to grip strength while working. The clinical history and the physical examination were dissonant, and a computed tomography scan revealed a nonunion of the hamulus. Intraoperatively, the nonunion of the hamate hook was identified and the bony ossicle excised. The flexor digitorum profundus and superficialis to the small finger were both ruptured. The flexor digitorum profundus tendon was repaired with a termino-terminal suture. The patient returned to work within 3 months without restriction. Six months postoperatively, the patient had no pain and achieved full active flexion of the small finger.