1. Department of Orthopaedics, Los Angeles County-University of Southern California Medical Centre, GNH 3900, 1200 N State Street, Los Angeles 90033, California, USA.
2. Department of Orthopaedics, Keck School of Medicine, University of Southern California, USC University Hospital, HCCI Suite 634, 1510 San Pablo Avenue, Los Angeles 90033-4608, California, USA.