Long-term outcomes, satisfaction, and survival rates of a medial pivot knee design

Background: The aim of this study was to evaluate the long-term clinical outcomes, satisfaction, perceived joint stability, and survival rates following medial pivot TKA. Methods: Data from TKAs performed at a single institution between 2008 and 2014 were retrospectively reviewed. Patients without consent were excluded. Inclusion: medial pivot TKA surgery. All patients received the same cemented Microport Advanced® and Evolution® Medial Pivot Knee System. Data collection comprised clinical and radiological outcomes, time of failure and/or death, surgical techniques (measured resection (MR) femur first technique following mechanical alignment principles vs. gap balancing (GB) tibia first technique preserving preoperative varus deformity up to 4°). Kaplan–Meier survival analysis compared survival between surgical techniques. Logistic regression evaluated surgical technique as a predictor for revision status. Risk analysis calculated relative and absolute risk differences between surgical techniques. Results: Of the 137 patients included in the final analysis, there were 24 deaths (17.5%), 15 lost to follow up (10.9%), four revisions (2.9%). The final follow up was obtained for 94 patients (68.6%) without revision. The mean survival was 16.14 years (95% CI: 15.96–16.32; standard error = 0.93) at the final follow up with a median of 11.32 years (IQR, 9.57–14.04). The Kaplan–Meier/Mantel–Cox indicated no difference in survival between MR and GB (Chi-squared = 0.02, P = 0.876). No other predictors for revision were found (CPAK (P = 0.78), aHKA (P = 0.55), MPTA (P = 0.73)). Nine (6.6%) patients stated that they were not satisfied with no difference for surgical technique (Chi-squared = 0.59, P = 0.824). Conclusions: The overall mean survival time was estimated to be 16.14 years with 97% survival rate.