1. Department of Orthopaedics and TraumatologyHelsinki University HospitalPL 900 Helsinki 00029 HUS Finland
2. Department of Orthopaedics and TraumatologyJyväskylä Central HospitalKeskussairaalantie 19 Jyväskylä 40620 Finland
3. Primary Health Care UnitKuopio University HospitalKuopio Finland
4. Folkhälsan Research CenterHelsinki Finland
5. Department of Orthopaedics and TraumatologyUniversity of HelsinkiPL 266 Helsinki 00029 HUS Finland