1 Surgical Intervention Trials Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK; Kellogg College, University of Oxford, Oxford OX3 7LD, UK. Electronic address: david.beard@ndorms.ox.ac.uk.
2 Malawi University of Science and Technology, Limbe, Malawi.