1. Hip Preservation Service, Hospital for Special Surgery, New York, New York, USA
2. Long Beach Orthopaedic Institute, Long Beach, California, USA
3. Department of Orthopaedic Surgery, Rochester, University of Rochester Medical Center, Rochester, New York, USA
4. Department of Orthopaedic Surgery, Brown University, Warren Alpert School of Medicine, Providence, Rhode Island, USA
5. Department of Orthopaedic Surgery, Harvard Medical School, Cambridge, Massachusetts, USA
6. Cleveland Clinic Florida, Weston, Florida, USA