Individualised total knee arthroplasty results in low reintervention rates for stiffness and instability in 1000 consecutive knees, regardless of intraoperative bone recuts or polyethylene thickness

PURPOSE: Individualised total knee arthroplasty (TKA) aims to restore the pre-arthritic anatomy, but concerns persist regarding ligament imbalance, as only two polyethylene insert thicknesses are available. This study aimed to evaluate revision and reintervention rates, especially for stiffness and instability, after individualised TKA, and whether intraoperative adjustments influenced these outcomes. METHODS: This retrospective cohort study included 1000 consecutive primary TKAs implanted using a CT-based individualised system with a 1-year minimum follow-up. The primary endpoint was any revision TKA. Secondary analyses evaluated reintervention for stiffness or instability and the association between reinterventions and (1) bone recuts and (2) polyethylene thickness. Survival was estimated with the Kaplan-Meier method. RESULTS: At a mean follow-up of 4.2 ± 1.8 years, 12 revision TKA (1.2%) and 29 reinterventions (2.9%) were recorded. All procedures were completed as planned with only two polyethylene insert thicknesses. Revision-free survival was 99.4% (95% confidence interval [CI] 98.7-99.7) at 1 year and 98.7% (95% CI 97.7-99.3) at 5 years. Reoperation-free survival was 98.1% (95% CI 97.0-98.8) and 97.0% (95% CI 95.7-97.9) at 1 and 5 years, respectively. Stiffness-related procedures occurred in nine cases (0.9%), and instability-related revision was observed in one case (0.1%). Bone recuts were performed in 42.8% of knees. No significant association was found between revision risk and bone recuts or polyethylene thickness. CONCLUSION: In this large consecutive cohort, individualised TKA was associated with low rates of revision and of reintervention for stiffness and instability. Intraoperative adjustments (bone recuts, polyethylene thickness changes) were not associated with a higher revision rate. LEVEL OF EVIDENCE: Level III, retrospective cohort study.