1. University of Oxford; Oxford UK
2. University College London; London UK
3. University Hospital Southampton; Southampton UK
4. Boston University School of Medicine, Boston, Massachusetts, and University of Erlangen-Nuremberg; Erlangen Germany
5. Boston University School of Medicine; Boston Massachusetts
6. University College London Hospitals, London, UK, and The Royal National Orthopaedic Hospital; Stanmore UK
7. University of Oxford, Oxford, UK, and University of Southampton; Southampton UK