Bone and Joint Disorders in Wild Japanese Macaques from Nagano Prefecture,Japan

I studied bone and joint disorders in wild Japanese macaques (Macaca fuscata fuscata) in order to discern some aspects of their life history from the skeletal material. The specimens comprise 107 nearly complete skeletons of subadults and adults that were killed as crop-raiding monkeys between 1997 and 1998 in Nagano Prefecture, Japan. The most frequent disorder is angular deformity due to fractures: 80 healed fractures in 31 of 52 males and 71 healed fractures in 26 of 55 females. Secondary osteoarthritis due to fractures is rare. Two males have osteochondritis dissecans bilaterally on the posterior surface of the lateral femoral condyles. Degenerative changes are common in the aged individuals. Fractures of the trunk—clavicle, scapula, vertebrae, ribs or hip—are frequent in the males. Contrarily, the majority of fractures in females are in the hands and feet. While most fractures in males appear to have occurred during adulthood, those in females occurred during childhood and senescence. Interindividual violence should not be regarded as a principal cause for fractures in males and females because there is no bite wound except perhaps for one case of an amputated digit. Fractures of the trunk in males were probably caused by impact forces against their shoulders or hips or both caused by rolling down a steep slope or falling out of trees, perhaps during intertroop transfers.