Stress fracture of the capitate.

Stress fracture of the capitate reports A 42-year-old male physical exercise teacher presented to his general practitioner (GP) with a 4-month history of bilateral wrist pain. He was unable to recall any specific episode of trauma, but the nature of his work as a gymnastics teacher required repeated dorsiflexion of both wrists. The pain was enough to keep him awake at night and he had developed stiffness and paraesthesia in both hands, particularly the left. On examination he had full range of movement at the left wrist joint, but had a positive phalen's sign. He was diagnosed by his GP as having carpal tunnel syndrome, however, treatment with local steroid injection and splinting had produced only partial relief. On presenting to the accident and emergency (A&E) department, physical findings were unchanged and radiographs of the left wrist showed a fracture of the capitate with established non-union (Fig. 1). Magnetic resonance imaging (MRI) confirmed non-union, but showed no evidence of avascular necrosis. (Fig. 2). In view of his symptoms of carpal tunnel syndrome the patient underwent bilateral carpal tunnel decompression, which was followed by complete resolution of the symptoms. Fractures of the capitate are uncommon, accounting for approximately 1.3% of all carpal fractures.1 When it does occur it is often associated with other carpal fractures or dislocations.2 The mechanism of injury is usually a fall onto the outstretched hand, direct violence to the dorsum of the hand or an extreme flexion force. One case of a stress fracture has previously been reported, occuring in a dock worker.3 Demonstration of capitate fractures may be dif-Fig. 1. Radiograph showing fracture of the capitate with 59 established non-union in left wrist. Fig. 2. MRI showing non-union although no evidence of avascular necrosis. ficult2 and if doubt exists then isotope bone scanning or computerized tomography may be helpful.4 Avascular necrosis is an uncommon occurrence. The proximal pole of the capitate receives its blood supply exclusively in a retrograde fashion across the waist, in a manner analogous to the scaphoid. This vascular supply may be disrupted after both major and relatively minor trauma (the naviculo-capitate syndrome).5 Avascular necrosis of the capitate resulting from dorsiflexion compression injuries in gymnasts may occur as a result of microfractures. Treatment for isolated fractures of the capitate is usually immobilization in a cast for 6 weeks2 with internal fixation reserved for cases with displacement or dislocation.6' Partial resection and inter-carpal fusion …