Traumatic volar dislocation of the trapezoid with acute carpal tunnel syndrome.

1 reported the first case of a dislocation of the trapezoid. Since that time there have been Ͻ25 reported cases in the literature. 2-24 Most dislocations are accompanied by a fracture of the adjacent carpals or metacarpals and usually are dorsal in direction. Palmar dislocation of the trape-zoid is distinctly more unusual, with Ͻ10 reported cases. 3, 4,6,22,24 A volar disloca-tion with accompanying acute carpal tunnel syndrome has not been reported. This article presents a case of volar dislocation with acute carpal tunnel syndrome. A 21-year-old right-hand-dominant man sustained a traumatic injury to his right wrist in a high-speed four-wheel accident. The patient did not recall the exact mechanism of injury, but the vehicle reportedly went end-over-end and he was thrown from the vehicle. He sustained no other injuries, except to his right wrist. He presented to our clinic 2 days later with pain in the wrist and numbness in the hand. Radiographs of the hand revealed a deformity of the trapezoid (Figure 1). A computed tomography (CT) scan identified a palmarly dislocated trapezoid occupying the carpal tunnel. Minute avulsion fragments were noted from the trapezium and capitate, but no other significant carpal or metacarpal injuries were identified (Figure 2). Clinical examination was notable for a swollen, tender wrist. Any motion of the wrist was painful, with significant discomfort on motion of the radial 3 digits. Sensation was decreased in the radial 3 digits and 2-point discrimination was 7-10 mm. Motor testing was significant for pain and was difficult to discern from neurologic injury. A clinical diagnosis was made of acute traumatic carpal tunnel syndrome. The patient underwent an open carpal tunnel release through a standard volar incision. The median nerve was identified and found to have evidence of compression in the carpal canal. The nerve was displaced volarly, having been stretched over the dislocated trapezoid. However, there was no intraneural hematoma or obvious discontinuity of the nerve or epineural sheath. With the median nerve carefully retracted, the trapezoid was identified through the same incision. To assist in reduction , a dorsal incision was made overlying the trapezoid. Reduction was then obtained with the wrist in slight flexion, longitudinal traction on the index and middle fingers, and volar manipulation of the trapezoid. Reduction was confirmed with fluoroscopy. Stabilization of the trapezoid was performed with multiple K-wires (Figure 3). Postoperatively the patient was placed into an initial thumb spica splint for …