Summary

The authors report 13 dogs with radiocarpal bone fracture.The lesion was bilateral in six cases and unilater-alin seven. Clinical and radiographic examination ofboth the carpal joints was performed. One or two fracturelines, sagittal oblique and dorsal, of the radial carpalbone were detected. CT examination of two radialcarpal bones helped in a better visualization of thefracture lines. A dorsal bone fragment of a fracturedradial carpal bone was removed in one dog. Histopathologyrevealed the presence of fibro-connective tissueon the fracture surface of the bone fragment. Thefibro-connective tissue did not seem to be the sequelto acute or chronic diseases, nor to any pathologicalhealing process. The cancellous bone of the fragmentwas normal as was the bulk of the articular cartilageexamined. A CT guided biopsy, including the sagittaloblique fracture surface of the radial carpal bone, wasalso performed. The specimens revealed the presenceof immature cancellous bone with diffuse immaturecartilage areas. The radial carpal bone has three separatecentres of ossification: the primitive radial carpalbone, the central and intermediate carpal bone. Thefusion of these centres occurs at 3-4 months of age.Histopathological findings suggest a possible "incompletefusion" of the centres of ossification rather thana true fracture of the radial carpal bone or alternativelya "fatigue fracture". A similar condition, involvingthe distal part of the humerus, was originally reportedin several Cocker Spaniel dogs, and more recently inRottweilers and Labrador Retrievers.