1. Department of Orthopaedic Surgery, Keck School of Medicine, The University of Southern California, Los Angeles, CA 90033, USA
2. Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN 55905, USA
3. Department of Orthopaedic Surgery, University of Chicago Medical Center, Chicago, IL 60612, USA
4. Department of Orthopaedic Surgery, Kaiser Permanente Bernard J. Tyson School of Medicine, Los Angeles, CA 91101, USA