1. Department of Orthopaedic Surgery, Box 492 UMHC, 420 Delaware Street, S. E. Minneapolis, Minnesota 55455, USA.
2. Departments of Orthopaedics and Surgery, University of Washington, Harborview Medical Centre, Seattle, Washington 98104, USA.
3. Colorado Orthopaedic Consultants, 1411 South Potomac Street, Suite 400, Aurora, Colorado 80012, USA.