Jordy van Sambeeck

Chapter 5 72 et al. 22 in their systematic review. Age at time of surgery might therefore be a factor for the risk of redislocation and patient reported outcome of surgery. In addition to these correlations, adolescent patients are expected to have more pliable osseocartilaginous structures than the older patients 23 , this might lead to less cartilage damage by focal aseptic necrosis, better malleability and therefore better clinical results in patients of a younger age. The main goal of this study was to evaluate the effect of age on patient reported outcome after a lateral facet elevating trochlear osteotomy in a large cohort. We hypothesized that lower age at time of surgery is associated with better patient reported outcomes. Methods Patients Data for this study was collected retrospectively. Patients who have undergone a lateral facet elevating trochlear osteotomy to restore patellar stability in Radboudumc, Nijmegen between 2005 and 2015 were included in this study. All operations were carried out by one senior orthopedic surgeon (AK) using the same surgical technique over time (described below). Indications for trochlear osteotomy were recurrent patellar dislocation or subluxation in the presence of a positive J-sign and radiographically confirmed trochlear dysplasia on a true lateral X-ray according to the criteria of Dejour 24 . Radiologically closed epiphyses stage 3 or 4 (scale range 0-4) was confirmed in all patients, this was scaled according to the method described by O’Connor et al. 25 . Stage 3 indicates recent union, stage 4 indicates complete union when remodeling has taken place and there is continuity of trabeculae form shaft to former epiphysis. This study was approved by the Medical Ethical Review Board of the Radboudumc, Nijmegen, The Netherlands (CMO 2015-1943). Methods of assessment The research team contacted each participant by phone to explain the study and have the participants complete patients reported outcome measurements (PROMs). A secured website was used to complete reports. The PROMs included the Kujala Knee Score (KKS) 1, 2 , the Short Form 36-item health survey (SF-36v1) 3, 4 and visual analogue scale (VAS) scoring pain, instability, disability and satisfaction. At time of surgery, no pre-operative or post-operative PROMs were collected. Due to the retrospective nature of this study, those data are lacking and are not included in the analysis.