Cruciate-Retaining versus Medial-Congruent Bearings in Total Knee Arthroplasty: A Retrospective Comparison of Ranges of Motion, Patient-Reported Outcomes, and Complications

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BACKGROUND: Cruciate-retaining (CR) total knee arthroplasty (TKA) demonstrates excellent long-term (≥ 10 years) outcomes. Medial-congruent (MC) bearings have gained popularity for enhancing midflexion stability and replicating native knee kinematics. In 2020, the senior author transitioned from CR to MC bearings while maintaining an identical surgical technique and implant system. This study aimed to compare short-term (≤ two years) clinical outcomes and complication rates between bearing types. METHODS: We retrospectively reviewed 1,057 consecutive primary TKAs [CR (n = 560), MC (n = 497)] performed by a single surgeon between 2013 and 2024. The posterior cruciate ligament was retained in all cases. Mean follow-up was 2.94 years (range, zero to 11.1) and 1.16 years (range, 0 to 4.69) for the CR and MC groups, respectively. Outcomes assessed were pre- and postoperative range of motion, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, EuroQol-5 Dimension, and EuroQol Visual Analog Scale (EQ-VAS). We also recorded postoperative complications (manipulation under anesthesia, fracture/dislocation, prosthetic joint infection, aseptic loosening, and soft tissue injury) and overall implant survivorship. Patients who did not have complete data were excluded from subgroup analyses. RESULTS: Arc range of motion improved similarly between groups. Improvements in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and EuroQol-5 Dimension were also similar, whereas EQ-VAS improvement was greater in the CR group (+12.7 versus +2.44; P < 0.01). Complication rates were low and similar between groups. Implant survivorship was excellent and similar in both groups (CR: 99.29%, MC: 99.40%). CONCLUSIONS: When controlling for surgical technique and implant system, CR and MC bearings yield comparable short-term functional outcomes and survivorship. The CR bearings demonstrated a greater improvement in EQ-VAS, but the generalizability of this finding remains uncertain. Increased medial congruence alone, therefore, may not substantially improve early clinical results in primary TKA.

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