Summary

Robotic-Assisted Total Knee Arthroplasty Achieves Superior Accuracy in Restoring Native Posterior Femoral Condylar Offset and Tibial Slope Compared to Conventional Technique

Abstract

Background

Restoring the native posterior femoral condylar offset (PFCO) and posterior tibial slope (PTS) during total knee arthroplasty (TKA) is crucial for enhancing knee flexion and optimizing postoperative range of motion.

Purpose

To compare robotic-assisted (RA-TKA) and conventional (C-TKA) total knee arthroplasty in terms of mechanical axis correction and restoration of PFCO and PTS.

Methods

This comparative, matched-group analysis included 60 patients undergoing TKA with a posterior-stabilized implant for primary osteoarthritis. Thirty patients received RA-TKA with functional alignment, and 30 underwent conventional C-TKA with mechanical alignment. Preoperative full-leg and lateral X-rays were obtained for each patient to assess alignment reproducibility. Postoperative evaluations occurred on the first day, and at 2- and 6-month follow-ups, following standard protocol. Changes in position were calculated as the difference between post- and pre-operative positions, with positive values indicating increases and negative values indicating decreases. All analyses were conducted by blinded researchers. Data normality was assessed using the Shapiro-Wilk test, and group differences were compared using independent samples t-tests. Statistical significance was set at p < 0.05.

Results

Both groups were comparable in terms of patient age and sex (p=0.87). The mean mechanical axis correction was 8.2±7.2º in the RA-TKA group and 4.9±5.3º in the C-TKA group, with no statistically significant difference between the groups (p=0.19; 95% CI, -1.03 to 5.06). The average change in PFCO was 0.58±4.6º in the RA-TKA group compared to -4.1±3.9º in the C-TKA group, a statistically significant difference (p<0.001; 95% CI, 2.47 to 6.89). The average change in PTS was 0.75±4º in the RA-TKA group versus -2.2±5.9º in the C-TKA group, also significant (p=0.02; 95% CI, 0.33 to 5.56).

Conclusions

Robotic-assisted TKA more accurately restores the native PFCO and PTS compared to conventional TKA, though both methods achieve similar results in mechanical axis correction.