1. Department of Trauma and Orthopaedics, Clarendon Wing, Floor A, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK.
2. Ludwing Boltsmann Institute for Experimental and Clinical Traumatology, Donaueschingenstrasse 13, A-1200 Vienna, Austria.
3. Department of Orthopaedic Surgery, University of Pittsburgh, Suite 1011, Kaufmann Medical Building, 3471 Fifth Avenue, Pittsburgh, Pennsylvania 15213–2582, USA.