Bicruciate-retaining versus cruciate-retaining total knee arthroplasty in implant fixation: a 10-year follow-up of a randomized RSA trial.

BACKGROUND AND PURPOSE: Bicruciate-retaining (BCR) total knee arthroplasty (TKA) aims to restore physiological knee kinematics and joint stability by preserving both cruciate ligaments, potentially improving patient satisfaction. However, long-term clinical outcomes and tibial component migration remain insufficiently understood. We therefore aimed to evaluate long-term implant fixation and clinical outcome after BCR-TKA compared with cruciate-retaining (CR) TKA. METHODS: We performed a long-term follow-up of a randomized controlled trial using radiostereometric analysis (RSA) to compare tibial implant migration between BCR-TKA and CR-TKA. The primary outcome was maximum total point motion (MTPM) of the tibial component, measured with model-based RSA at 3 months, 1, 2, 5, and 10 years. Secondary outcomes included the Oxford Knee Score (OKS) and Forgotten Joint Score (FJS) at identical time points. Mortality, reoperations, and revisions were recorded. RESULTS: 25 patients were included in each group. At 10 years, the estimated mean MTPM was 0.88 mm (95% confidence interval [CI] 0.64-1.12) in the BCR group and 0.64 mm (CI 0.40-0.88) in the CR group (between-group difference -0.23 mm, CI -0.57 to 0.10). Estimated changes in OKS and FJS showed no evidence of differing longitudinal trajectories between groups. 2 revisions occurred in the BCR group, whereas none occurred in the CR group. CONCLUSION: No significant differences were detected between BCR-TKA and CR-TKA in tibial implant migration or patient-reported outcomes over the 10-year follow-up. In contrast, the incidence of complications was higher in the BCR group, indicating that careful patient selection and optimization of surgical strategies remain important for BCR-TKA.