1. Department of Laboratory Medicine, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, 87-100 Torun, Poland
2. Department of Orthopaedics, KoMed Poddebice Health Center, 99-200 Poddebice, Poland
3. Department of Surgical and Perioperative Sciences, Division of Orthopaedics, Sunderby Research Unit, Umeå University, 971 80 Luleå, Sweden
4. Clinical Epidemiology Unit, Orthopedics, Department of Clinical Sciences Lund, Lund University, 223 62 Lund, Sweden