1. Department of Orthopedics and Traumatology, Päijät-Häme Central Hospital, Lahti, Finland
2. Department of Orthopedics and Traumatology, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
3. Department of Public Health, University of Helsinki, Helsinki, Finland
4. Department of Orthopedics and Traumatology, North Kymi Hospital, Kouvola, Finland