Introduction. Trochleoplasty is an effective surgical procedure for patients with severe trochlear dysplasia and recurrent patella instability. Previous work has suggested patients demonstrate early improvements in knee function and quality of life. However, concerns regarding longer term outcomes due to the development of stiffness and patellofemoral osteoarthritis remain a concern for these patients. Our aim was to assess mid-term patient-reported outcome and quality of life measures for trochleoplasty performed at a single centre for severe trochlear dysplasia. Methods. Retrospective review of 28 knees (23 patients) having undergone trochleoplasty for severe trochlear dysplasia were reviewed. Due to the non-parametric nature of the data, median and interquartile range (IQR) were determined for pre-operative and mid-term follow-up scores. Statistically significant differences between groups were assessed using paired Wilcoxon-signed rank test with statistical significance set at p<0.05. Data were analysed using a statistical software package (IBM® SPSS® Statistics 26.0). Results. Median time from surgery to follow-up for all patients in the series was 5.3 years (IQR 3.9 – 7.0 years). Median pre-operative Kujala score improved from 57.0 (IQR 45 – 66) to 96.3 (IQR 83 -100). Median pre-operative IKDC score improved from 42.6 (IQR 35.9 – 51.3) to 92.6 (IQR 71.6 – 98.7). Median EQ-5D score also improved from 0.691 (IQR 0.414 – 0.727) to 1.000 (IQR 0.8178 – 1.000). Improvement in Kujala scores, IKDC scores and EQ-5D were all statistically significant with p<0.001 in all domains. Discussion. Our data suggests patients experience significant improvements in knee function and quality of life following trochleoplasty surgery for severe dysplasia. We demonstrate an absolute improvement in scores at a mean of 5.3 years follow-up of 39.3 points for Kujala, 50 for IKDC and 0.309 for EQ-5D. Minimal clinically important differences (MCID) have been reported to be in the region of 10 for the Kujala score, 8.8–15.6 for IKDC and 0.085 for EQ-5D. Our data shows improvements which far exceed the published MCID, suggesting trochleoplasty confers a large treatment effect and patients benefiting from sustained improvements in knee function and overall quality of life at mid-term follow-up. Conclusion. Following trochleoplasty for severe trochlear dysplasia, patient reported outcomes demonstrate continued improvements in knee function and quality of life at mid-term (5-year) follow-up. There is a large absolute treatment effect which likely impacts on both physical and psychological wellbeing for these patients. Continued surveillance of patient reported outcomes in this clinically complex cohort is indicated

Objective. Overviewing the literature, pain and redislocation after surgical treatment of patellofemoral instability (PFI) is described with up to 30 %, especially with techniques involving the extensor mechanism, the lateral retinaculum or the medial vastus. However, outcome data about revision surgery is missing. Therefore, it was the purpose of this prospective study to evaluate the clinical outcome after revision surgery with an isolated or a combined reco. of the medial patellofemoral ligament (MPFL) with a follow up of 12 months. The indication for additional procedures such as distal femoral osteotomies (DFO), trochleoplasty, reclosing of the lateral retinaculum (RLR) or lateralisation of the tuberosity (LT) were performed depending on the clinical and radiological pathomorphologies. Methods. In between 3/07–4/09, 42 pat. with a mean age of 24 years (13–46ys) were revised due to persistent PFI after mean 1.8 failed previous operations (lateral release, medial gather/VMO-distal., medial. of the tuberosity) in our department. An isolated reco. of the MPFL was performed in 15 cases, while a combination with a DFO due to massive femoral axis deformity (n=5), trochleoplasty due to a convex trochlear morphology (n=1) and/or LT (n=4) and/or RLR due to medial instability or lateral pain (n=22) was done in 27 cases. The clinical result was evaluated by the pre- and postop. IKDC/Kujala/Tegner-score and by a subjective questionnaire. Radiologically, the patellashift/-tilt/-height and level of the eventual degeneration were defined preop. and at the point of follow up with the help of straight lateral radiographs and by MRI. Significance level was set at p=.05, statistical calculation was done by the use of the t-test. Results. 87 % were very satisfied/satisfied with the treatment., None redislocation of the patella occurred during the follow up. We could evaluate a significant decrease of the pain during daily activities. The IKDC/Kujala/Tegner score have shown a significant increase overall. However, a significant difference concerning the scores could not be noticed in between the groups without and with additional procedures. Patellar shift, tilt, height decreased significantly to anatomical values. The level of preexisting degeneration showed no aggravation. Conclusion. Since it is known that PFI is a multifactorial problem, revision surgery should set about only after comprehensive examinations. Regarding our results, isolated or combined MPFL reco. seems to be a very effective treatment of recurrent patella dislocation and results in a significant increase of stability, functionality as well as in a reduction of pain. Additional pathomorphologies of the bony structures or a lateral release, which causes pain or an aggravation of instability, have to be addressed additionally to reach same results like with an isolated therapy. Level of Evidence. II