[1] Uppsala Univ, Vestmanland Cty Hosp, Ctr Clin Res, SE-72189 Vasteres, Sweden
[2] Lund Univ, Univ Hosp, Dept Clin Sci Lund, Orthopaed, Lund, Sweden
[3] Montgomery Cty Infants & Toddlers Program, Olney, MD USA
[4] Univ Ulster, Inst Nursing & Hlth Res, Sch Hlth Sci, Coleraine, Londonderry, North Ireland
[5] Sunny Hill Hlth Ctr Children, Vancouver, BC, Canada