Hook of Hamate Fractures: Critical Evaluation of Different Therapeutic Procedures

Evaluation Of Therapeutic Strategies In Hook Of Hamate Fractures

Oliver Scheufler, M.D., Reimer Andresen, M.D., Sebastian Radmer, M.D., Detlev Erdmann, M.D., Günter Germann, M.D., Ph.D.

Fractures of the hamate hook are rare events, making up only 2-4% of all carpal fractures. They may occur by different mechanisms, including a directly applied force in a fall or crush injury, a shearing force applied by the extrinsic flexor tendons of the ring and small finger, repeated microtrauma during forceful grip in several sports using a racquet or bat, and combinations of these forces 1. Although these fractures are uncommon, the increasing popularity of golf and other racquet sports has led to a higher incidence of stress fractures of the hamate hook. Approximately one third of these stress fractures are caused by golf 2. Clinical signs of hamate hook fractures include pain in the ulnar palm aggravated by grasp and dorsoulnar deviation, pain with deep palpation over the hook, and painful flexion of the ring and small finger caused by tendinitis of the finger flexors. Clinical diagnosis is confirmed by standard and special radiographs, CT, and MRI, but is often delayed when patients seek medical attention only after symptoms persist 3. Hook of hamate fractures can be treated conservatively or operatively. Some advocate conservative treatment by lower arm splinting as the treatment of choice in nondisplaced fractures 4, while others believe that fragment healing is the exception and nonunion the rule with conservative treatment 5. Displaced fractures should be treated operatively, whereby excision of the fragment or open reduction and internal fixation (ORIF) are described.

A hamulus ossis hamati fracture was verified in 14 patients (mean age: 42 years; range: 21 - 73 years) including 11 males and 3 females (Table I). In 11 patients (78.6%) hamate hook fractures resulted from a direct blow to the proximal part of the palm during different daily activities. In 3 patients (21.4%) stress fractures occurred during sports activities, involving the nondominant hand while swinging a golf club in 2 patients and the dominant hand while swinging a tennis racquet in 1 patient. Diagnostic imaging included conventional radiographs in two planes in all of the 14 patients, carpal tunnel view in 7 patients (50%), CT scan in 9 patients (64.3%), and MRI in 5 patients (35.7%). All patients presented a fracture of the hook close to the base.

In 6 patients (42.9%) conservative treatment was initiated immediatly after trauma with a lower arm cast for 6 weeks, in 5 patients (35.7%) the fragment was excised primarily, and in 3 patients (21.4%) an ORIF was performed primarily using a screw. 5 of the 6 patients (83.8%) treated conservatively developed nonunion of the fracture with persisting clinical symptoms. All of those patients were operated secondarily, whereby 3 patients underwent excision and 2 patients ORIF with screw fixation. All surgical treatments included release of Guyon´s canal. The group of patients undergoing excision received functional treatment with physiotherapeutic exercises without any limitation of movement. The patients undergoing ORIF were immobilized with a lower arm cast for 2 weeks followed by physiotherapy and were instructed to avoid any strain of the injured hand for a total of 6 weeks. All 8 patients operated primarily were asymptomatic three months after surgery. In all 5 cases of secondary surgery after failed conservative treatment elemination of symptoms was achieved.

The clinical outcome of patients treated conservatively was disappointing. Therefore, primary surgical treatment is recommended. In our patients excision and ORIF led to comparable results. Important considerations in the choice of treatment for hamate hook fractures are the time of diagnosis, hook displacement, and vascularity of the fragment 6. Other important considerations are lifestyle and working requirements, because conservative treatment requires a long time of immobilization with subsequent physiotherapy and a high risk of nonunion, and fragment excision has been associated with weakened grasp, impaired sensibility, and residual pain with considerable frequency. ORIF, employing a compression screw of proper size, may be advantageous in several ways. It allows exact repositioning of the fracture and restitution of the complex anatomic structures linked to the hamate hook. It also reestablishes the hamate hook as a pulley for flexor tendon function of the small and ring finger, especially in ulnar deviation and power grip, thereby restoring hand function 7.

1. Walsh, J. J, 4th, Bishop, A. T. Diagnosis and management of hamate hook fractures: Hand Clin. 16: 397, 2000. 2. Guha, A. R., Marynissen, H. Stress fracture of the hook of the hamate. Br J. Sports Med. 36: 224, 2002. 3. Andresen, R., Radmer, S., Scheufler, O., Banzer, D. Imaging and therapy of hamulus- ossis-hamati fracture. Röntgenpraxis 54: 114, 2001. 4. Whalen, J. L., Bishop, A. T., Linscheid, R. L. Nonoperative treatment of acute hamate hook fractures. J. Hand Surg. [Am] 17: 507, 1992. 5. David, T. S., Zemel, N. P., Mathews, P. V. Symptomatic, partial union of the hook of the hamate fracture in athletes. Am. J. Sports Med. 31: 106, 2003. 6. Failla, J. M. Hook of hamate vascularity: vulnerability to osteonecrosis and nonunion. J. Hand Surg. [Am] 18: 1075, 1993. 7. Demirkan, F., Calandruccio, J. H., Diangelo, D. Biomechanical evalutation of flexor tendon function after hamate hook excision. J. Hand Surg. [Am] 28: 138, 2003.

Table I. Patients with Hook of Hamate Fractures Pat. Age Sex Fracture Trauma Initial Secondary Treatment Treatment 1 24 male nondisplaced hockey bat contusion conservative excision 2 56 male nondisplaced car door contusion conservative excision 3 67 male nondisplaced stress fracture (golf player) conservative excision 4 42 female nondisplaced bicycle accident conservative none 5 29 male nondisplaced fall conservative screw 6 35 male displaced bicycle accident conservative screw 7 51 male nondisplaced stress fracture (tennis) excision - 8 73 male nondisplaced stress fracture (golf) excision - 9 22 male displaced bicycle accident excision - 10 62 female displaced bicycle accident excision - 11 31 female nondisplaced fall excision - 12 21 male nondisplaced motorcycle accident screw - 13 24 male nondisplaced fall from roof screw - 14 51 male nondisplaced fall screw - Fig. 1a

Fig. 1b

Fig. 1 Patient no. 14 with nondisplaced hook of hamate fracture in the right hand: standard radiograph in anteroposterior projection, b) axial CT scan

Fig. 2a

Fig. 2b

Fig. 2 Patient no. 14 after ORIF with screw fixation of the fragment: a) standard radiograph in anteroposterior projection, b) lateral projection