[1] Leiden University Medical Center,Department of Neurosurgery
[2] VU University Medical Center,Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research
[3] Maastricht University Medical Center,Department of Orthopedic Surgery
[4] Hospital Vall d’Hebron,Department of Orthopedic Surgery
[5] University Medical Center Utrecht,Department of Orthopedic Surgery
[6] Medical Center Haaglanden,Department of Neurosurgery
[7] VU University,Department of Health Sciences, Faculty of Earth and Life Science and EMGO Institute for Health and Care Research