Proximal Carpal Row Dislocation: A Case Report

Abstract

Carpal dislocations commonly occur as the result of high-energy axial loading of the forearm with the wrist extended. There exists several variants of carpal dislocations with the most commonly observed being those about the lunate. Perilunate dislocations and fracture dislocations were first characterized by Mayfield in 1980 and represent a spectrum of traumatic carpal dislocation beginning radial and progressing to the ulnar side of the wrist (Mayfield et al. J Hand Surg [Am] 5:226–241, 1980). The path of energy takes a predictable pattern around the lunate from the scapho-lunate ligament, into the mid-carpal joint and then to the luno-triquetral joint. The final stage is volar dislocation of the lunate into the carpal canal. These complex fracture dislocations are unstable and require operative fixation through open reduction and with internal fixation (Herzberg et al. J Hand Surg [Am] 18:768–779, 1993; Adkison and Chapman Clin Orthop Rel Res 164:199–207, 1982). Other types of carpal dislocations have been described; however, these are much less frequently encountered (Green and O'Brien Clin Orthop Rel Res 149:55–72, 1980; Irwin et al. J Hand Surg [Br] 20B:746–749, 1995; Rosado J Bone Joint Surg 48B:504–506, 1966). These also include mid-carpal instability and longitudinal (axial) instability and have been described extensively in the literature (Norbeck et al. J Hand Surg 12A:509–514, 1987; Primiano and Reef J Bone Joint Surg 56A:328–332, 1974; Garcia-Elias et al. J Hand Surg 14A:446–457, 1989; Taleisnik Hand Clinics 3:51–68, 1987). Carpal instabilities can be characterized as dissociative which disrupt joints within a carpal row, or as non-dissociative which have dislocations or subluxations between carpal rows (Dobyns and Cooney 1998). We report a case of complex carpal injury non-dissociative involving dislocation of the entire proximal carpal row volarly. To our knowledge such a variation of complex carpal dislocation has not been reported. This injury represents yet another possible variant encountered when treating high-energy injuries to the wrist.