1. Orthopaedic Surgeon, 509 N. Garfield, Midland, Texas 79701.
2. Associate Professor, Department of Orthopaedics, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, Texas 78284. Address correspondence to Dr. Heckman.
3. Professor and Chairman, Department of Orthopaedics, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, Texas 78284.