[1] Univ Bristol, Bristol Med Sch, Musculoskeletal Res Unit, Translat Hlth Sci, Bristol BS10 5NB, Avon, England
[2] Univ KwaZulu Natal, Coll Hlth Sci, Sch Clin Med, Dept Geriatr,Div Internal Med, Durban, South Africa
[3] Univ Witwatersrand, Fac Hlth Sci, Sch Clin Med, MRC Wits Dev Pathways Hlth Res Unit,Dept Paediat, Johannesburg, South Africa
[4] Univ Witwatersrand, Fac Hlth Sci, Sch Clin Med, Div Orthopaed Surg,Dept Surg, Johannesburg, South Africa
[5] Charlotte Maxeke Johannesburg Acad Hosp, Div Orthopaed Surg, Johannesburg, South Africa
[6] London Sch Hyg & Trop Med, Clin Res Dept, London, England
[7] Biomed Res & Training Inst, Harare, Zimbabwe
[8] Univ Southampton, MRC, Lifecourse Epidemiol Unit, Southampton, Hants, England
[9] MRC, Elsie Widdowson Lab, Cambridge, England