[1] Univ Jyvaskyla, Dept Hlth Sci, Viveca Bldg,POB 35, Jyvaskyla 40014, Finland
[2] Cent Finland Hlth Care Dist, Dept Phys Med & Rehabil, Keskussairaalantie 19, Jyvaskyla 40620, Finland
[3] Vrije Univ Amsterdam Med Ctr, Dept Rehabil Med, POB 7057, NL-1007 MB Amsterdam, Netherlands
[4] Vrije Univ Amsterdam Med Ctr, Dept Psychiat, POB 7057, NL-1007 MB Amsterdam, Netherlands
[5] Cent Finland Hlth Care Dist, Dept Orthopaed Med, Keskussairaalantie 19, Jyvaskyla 40620, Finland
[6] Tampere Univ Hosp, Dept Orthopaed & Trauma, POB 2000, Tampere 33521, Finland