1. Department of Orthopaedics, James Cook University Hospital, Marton Road, Middlesborough, Cleveland TS4 3BW, UK.
2. Department of Accident and Emergency, Bradford Royal Infirmary, Duckworth Lane, Bradford, West Yorkshire BD9 6RJ, UK.
3. Department of Orthopaedics, St James’s University Hospital, Beckett Street, Leeds LS9 7TF, UK.
4. Department of Medicine, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK.