1. Department of Orthopedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
2. Department of Orthopedic Surgery, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
3. Department of Orthopaedics, West Virginia University School of Medicine, Morgantown, West Virginia
4. Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
5. Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota