[1] Erasmus Univ, Dept Orthopaed & Sports Med, NL-3000 CA Rotterdam, Zuid Holland, Netherlands
[2] Aalborg Univ, Dept Clin Med, Res Unit Gen Practice Aalborg, Aalborg, Denmark
[3] Aspetar Qatar Orthopaed & Sports Med Hosp, Aspetar Sports Groin Pain Ctr, Doha, Ad Dawhah, Qatar
[4] Karolinska Inst, Div Physiotherapy, Stockholm, Stockholm Count, Sweden
[5] Univ Bristol Sch Med, Populat Hlth Sci, Bristol, Avon, England