Yen-Jen Chen1, Hui-Yi Chen2, Horng-Chaung Hsu1. 1. Department of Orthopedic Surgery, China Medical University Hospital, No. 2, Yuh-Der Rd, Taichung, Taiwan 404, Republic of China; School of Medicine, China Medical University, No. 91, Hsueh-Shuh Rd, Taichung, Taiwan 40402, Republic of China. 2. Department of Radiology, China Medical University Hospital, No. 2, Yuh-Der Rd, Taichung, Taiwan 404, Republic of China.