Dorsal 80 degrees proximal 30 degrees lateral-palmarodistal medial oblique view for screw fixation of the accessory carpal bone

摘要

Accessory carpal fracture is quite uncommon ahd generally occurs in jumping and steeple chase horses but may also be seen after collisions or falls in any breed. Most fractures occur in a vertical and frontal plane through the lateral groove formed by the tendon of the ulnaris lateralis muscle. Horses usually have pronounced lameness after injury, and an effusion of the carpal flexor sheath may be present. The caudal fragment is pulled dorsally by the flexor carpi ulnaris muscle, creating a fibrocartilaginous nonunion. Treatment options include conservative management or surgical fixation with screws or plates. It has been hypothesized that attempts at surgical repair have been infrequent because of the location of the bone, the narrow space for screw placement, the concave shape of the accessory carpal bone, the lateral groove formed by the tendon of the ulnaris lateralis muscle, and the satisfactory results obtained with conservative treatments. According to some investigators, a relatively small number of horses recover their athletic potential after conservative and surgical treatment because of the close lying carpal tunnel and the shape of the bone. The aim of the present study was to develop the dorsal 80 deg proximal 30 deg lateral-palmarodistal medial oblique (D80 deg Pr30 deg L-PaDiMO) radiographic projection for optimal control of lag screw fixation of fractures of the accessory carpal bone. Combined with conventional views, this D80 deg Pr30 deg L-PaDiMO view can provide a 3-dimensional evaluation of the bone allowing reproducible fixation of simple frontal fractures with two 3.5-mm cortical bone screws applied in lag fashion from the palmar aspect.