1 Department of Physical and Rehabilitation Medicine, Institute of Clinical Medicine, University of Oulu, and Medical Research Center Oulu, Box 5000, 90014 Oulu, Finland.
2 Institute of Health Sciences, Biocenter Oulu, University of Oulu, Box 5000, 90014 Oulu, Finland.
3 Department of Orthopaedics and Traumatology, University of Hong Kong, Professorial Block, 5th Floor, 102 Pokfulam Rd, Pokfulam, Hong Kong, SAR, China.
4 Department of Physical and Rehabilitation Medicine, Institute of Clinical Medicine, University of Oulu, and Medical Research Center Oulu, Box 5000, 90014 Oulu, Finland. Electronic address: Jaro.Karppinen@ttl.fi.