[1] Univ Groningen, Univ Med Ctr Groningen, Dept Orthoped, NL-9700 RB Groningen, Netherlands
[2] Amphia Hosp, Dept Orthoped, Breda, Netherlands
[3] Ropcke Zweers Hosp, Dept Orthoped, Hardenberg, Netherlands
[4] Martini Hosp, Dept Orthoped, Groningen, Netherlands
[5] Univ Groningen, Univ Med Ctr Groningen, Dept Gen Practice, NL-9700 RB Groningen, Netherlands
[6] Univ Groningen, Univ Med Ctr Groningen, Dept Hlth Sci Community & Occupat Med, NL-9700 RB Groningen, Netherlands