1. Sports Medicine Unit, Department of Community Medicine and Rehabilitation, Umeå University, 90187 Umeå, Sweden
2. Alfredson Tendon Clinic, Capio Ortho Center Skåne, 21532 Malmö, Sweden
3. Capio Ortho Center Skåne, 21532 Malmö, Sweden
4. Anatomy Section, Department of Integrative Medical Biology, Umeå University, 90187 Umeå, Sweden
5. Institute for Sports Science, Würzburg University, 97082 Würzburg, Germany
6. Private Orthopaedic Spine Center, 97080 Würzburg, Germany
7. Department of Health, Medicine and Caring Sciences, Linköping University, 58183 Linköping, Sweden