[1] Univ Basel Hosp, Dept Orthopaed, CH-4031 Basel, Switzerland
[2] Harvard Univ, Beth Israel Deaconess Med Ctr, Sch Med, Ctr Adv Orthoped Studies, Boston, MA 02215 USA
[3] Tokyo Univ Hosp, Dept Orthopaed Surg, Tokyo 113, Japan
[4] Orthopaed Univ Clin Heidelberg, Dept Orthopaed, Heidelberg, Germany