Preoperative flexion contracture does not impair outcomes or early revision rates following robotic total knee arthroplasty with functional alignment

Abstract

PURPOSE: Preoperative flexion contracture remains a challenging deformity in total knee arthroplasty (TKA). This study aimed to evaluate whether the presence of preoperative flexion contracture influences outcomes and early revision rates following robotic-assisted TKA performed with functional alignment (FA) principles. METHODS: This retrospective comparative study analysed 190 patients who underwent robotic-assisted TKA using a computed tomography-based FA strategy. Patients were grouped based on intraoperative measurement of flexion contracture: ≥10° (study group; 43 patients) and <10° (control group; 147 patients). Clinical outcomes, intraoperative data, and early revision rates were assessed at a minimum 24-month follow-up. RESULTS: The study group exhibited significantly more varus alignment intraoperatively and required greater lateral tibial and posterior medial femoral resections. Preoperative knee flexion was lower in the contracture group (110° vs. 120°, p = 0.0018), and postoperative flexion remained slightly reduced (120° vs. 130°, p = 0.05). Flexion contracture at follow-up was 1° in the study group versus 0° in controls (p = 0.04). However, no significant differences were observed in Knee Society Scores, Forgotten Joint Score, Kujala score, or early revision rates. All-cause revision rates were similar (97.67% vs. 98.64%, p = 0.66), with a hazard ratio of 1.85 (95% CI: 0.12-27.72). Aseptic survivorship was 100% in the contracture group versus 99.32% in controls (p = 0.59). CONCLUSION: Patients with preoperative flexion contracture ≥ 10° achieved comparable mid-term outcomes and early survivorship to those without contracture following robotic-assisted TKA using FA. These findings support FA as a reliable strategy to manage complex deformities without the need for soft tissue releases. LEVEL OF EVIDENCE: Level III.