1. Department of Orthopedics, Örebro University Hospital, Örebro, Sweden;
2. Department of Biomedical Sciences, University of Sassari, Sassari, Italy;
3. Department of Electronics and Telecommunications, Politecnico di Torino, Torino, Italy;
4. GPEM srl, Alghero, Italy;
5. Clinical Epidemiology and Biostatistics, School of Medical Sciences, Örebro University, Örebro, Sweden;
6. Department of Orthopedics, Skaraborg Hospital Skövde and Mölndal Hospital Sahlgrenska, Gothenburg, Sweden