1. Euroclinic Children's Hospital, Lemesou; Athens; Greece
2. Department of Orthopaedics; Clinical Sciences Lund; Lund University; Lund; Sweden
3. RC Syd, National Centre for Quality Registers; Skåne University Hospital; Lund; Sweden
4. Department of Paediatrics; Clinical Sciences Lund; Lund University; Lund; Sweden