Comparison of Radiographic and Patient-Reported Outcomes in Robotic-Assisted Versus Manual Total Knee Arthroplasty Using Medial-Congruent Bearing

TL;DR

This study compares robotic-assisted and manual knee replacement surgeries using a specific bearing design, finding similar patient outcomes but better alignment with the robotic method.

Contribution

The study provides evidence that robotic-assisted TKA with medial-congruent bearings achieves comparable patient-reported outcomes but better sagittal alignment than manual TKA.

Findings

RA-TKA and M-TKA showed similar 12-month improvements in patient-reported outcomes (OKS and KOOS-JR).

RA-TKA had fewer posterior tibial slope outliers compared to M-TKA.

Operative time was longer for RA-TKA but baseline characteristics and liner thickness were comparable.

Abstract

Background: Total knee arthroplasty (TKA) effectively relieves pain in end-stage osteoarthritis, yet a proportion of patients remain dissatisfied despite advances in surgical technique. Medial-congruent (MC) bearings are designed to recreate native medial-pivot kinematics, which depend on appropriate medial compartment soft tissue tension. Robotic-assisted TKA (RA-TKA) has been shown to improve the accuracy and soft tissue balance. However, evidence of its additional benefits in MC TKA remains limited. Methods: We retrospectively identified consecutive primary TKAs with the same MC bearing performed between April 2022 and June 2024 at a tertiary center. After performing 1:1 propensity score matching to reduce baseline imbalance, 36 patients who received RA-TKA and 36 who underwent manual TKA (M-TKA) were included. Primary outcomes were evaluated with the 12-month Oxford Knee Score (OKS) and KOOS-JR. Secondary outcomes included radiographic alignment parameters, outlier rates, operative time, liner thickness, and hospital stay. Results: Baseline characteristics and liner thickness were comparable, and operative time was longer in the RA-TKA group than in the M-TKA group. Both RA-TKA and M-TKA produced significant 12-month improvements in OKS and KOOS-JR with no difference in mean scores. RA-TKA had fewer posterior tibial slope outliers (mean slope 4.3° ± 1.8 vs. 5.9° ± 3.1; outlier rate 16.7% vs. 41.7%; p = 0.02), whereas coronal alignment parameters did not differ between groups. Conclusions: RA-TKA with MC bearing provides functional outcomes comparable to M-TKA and may decrease sagittal alignment variability; long-term follow-up studies are needed to determine whether this potential benefit translates into sustained functional gains or improved implant survivorship.

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