Superior One-year Forgotten Joint Scores with cruciate-retaining mobile bearings versus posterior-stabilized mobile and fixed bearings in a contemporary total knee system

Background: Total knee arthroplasty (TKA) mainly involves the femoral, tibial, and bearing implants. Bearings are categorized by posterior cruciate ligament (PCL) status (cruciate-retaining [CR] vs. posterior-stabilized [PS]) and motion (mobile vs. fixed). This study assessed the impact of three bearing combinations (CR Mobile, PS Mobile, and PS Fixed) on one-year patient-reported outcome measures (PROMs) following TKA.

Methods: In this retrospective analysis of 486 TKAs using the same prosthesis with varied bearings, patients were grouped as CR Mobile, PS Mobile, and PS Fixed. Patient characteristics, preoperative, and one-year postoperative PROMs (Forgotten Joint Scores [FJS] and Knee Society Scores [KSS], and Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), were collected. Multivariate analysis was conducted to assess the impact of bearing type on one-year PROMs.

Results: The multivariate regression model showed that bearing type significantly impacted the one-year FJS, with CR Mobile showing higher scores than PS Mobile and PS Fixed bearings (p < 0.001). However, bearing type did not significantly influence one-year KSS and WOMAC scores (all p > 0.05).

Conclusion: This study was the first to analyze the impact of the combination of PCL status and bearing motion in TKA. Bearing type selection had an impact on the one-year postoperative FJS, particularly favoring CR Mobile bearings. Other PROMs were not affected by the choice of bearing type.