Ali Narvani MB BS BSc MRCS(Eng) MSc(Sports Med) FRCS (Tr & Orth) MFSEM(UK) Consultant Shoulder and Elbow Surgeon, Ashford and St Peter's Hospital, Surrey Panos Thomas MD CCSTOrth MFSEM FRCS Consultant Orthopaedic Surgeon, The Whittington Hospital, London Bruce Lynn BSc PhD Emeritus Professor of Physiology, UCL, London