1. Associate Professor of Orthopedic Surgery, Mayo Medical school, Rochester, Minnesota. To whom all correspondence should be addressed, at the Department of Orthopedics, Mayo Clinic, Rochester, Minnesota 55905.
2. Resident in Orthopedics, Mayo Graduate School of Medicine, Rochester, Minnesota. Present address: Orthopedic Clinic, 808 South 52nd Street, Omaha, Nebraska 68124.
3. Professor of Radiology, Mayo Medical School, Rochester, Minnesota.