1. Orthopaedic Group, P.C., Mobile, AL 36608, USA
2. Research Center at Hopital du Sacre-Coeur de Montreal, Montreal, Canada
3. Department of Orthopaedic Surgery, Lenox Hill Hospital, New York, NY 10007, USA
4. Orthopedic Surgery and Traumatology Department, University Hospital of Navarra, Pampola, Spain
5. Clinica Ortopedica, S. Martino Hospital, Genoa, Italy