1. Department of Orthopaedic Surgery, Boston Medical Center, Boston, Massachusetts, USA.
2. Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York, USA.
3. Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
4. Department of Orthopaedic Surgery, Keck School of Medicine at USC, Los Angeles, California, USA.