The Parker Institute, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark. Electronic address: else.marie.bartels@regionh.dk. Bone and Cartilage Research Unit, Arthropôle Liège, Institute of Pathology, Level 5, CHU Sart-Tilman, 4000 Liège, Belgium; Department of Physical Therapy and Rehabilitation, Princess Paola Hospital, Vivalia, Marche-en-Famenne, Belgium. Electronic address: yhenrotin@ulg.ac.be. The Parker Institute, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark; Faculty of Health Science, University of Copenhagen, Denmark. Electronic address: henning.bliddal@regionh.dk. Bone and Cartilage Research Unit, Arthropôle Liège, Institute of Pathology, Level 5, CHU Sart-Tilman, 4000 Liège, Belgium. Electronic address: prescilia.centonze@ulg.ac.be. The Parker Institute, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark; Department of Physical and Occupational Therapy, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark. Electronic address: marius.henriksen@regionh.dk.