[1] Univ Oxford, Botnar Res Ctr, Nuffield Dept Orthopaed Rheumatol & Musculoskelet, Windmill Rd, Oxford OX3 7LD, England
[2] Univ Oxford, Nuffield Dept Orthopaed Rheumatol & Musculoskelet, Oxford, England
[3] Univ Penn, Perelman Sch Med, Dept Med, Div Rheumatol, Philadelphia, PA 19104 USA