[1] Bispebjerg Hosp, Dept Phys Therapy, Musculoskeletal Rehabil Res Unit, Copenhagen, Denmark
[2] Univ Copenhagen, Bispebjerg Hosp, IOC Sports Med, Dept Orthopaed Surg M, Bldg 8,Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark
[3] Univ Copenhagen, Fac Hlth Sci, Ctr Hlth Aging, Bldg 8,Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark
[4] Univ Copenhagen, Inst Publ Hlth, Res Unit, Copenhagen, Denmark
[5] Univ Copenhagen, Inst Publ Hlth, Dept Gen Practice, Copenhagen, Denmark
[6] Danish Assoc Rheumatism, SANO, Ctr Hlth & Rehabil, Copenhagen, Denmark
[7] Inst Social Informat, Copenhagen, Denmark
[8] Boston Univ, Sch Publ Hlth, Hlth & Disabil Res Inst, Boston, MA USA
[9] Zealand Univ Hosp, Dept Rheumatol, Roskilde, Denmark