Impact of flexion contracture severity on early outcomes of computer-navigated total knee arthroplasty: a retrospective cohort study.

Abstract

This study assessed the accuracy, safety, and early clinical outcomes of computer-navigated total knee arthroplasty (TKA) in the treatment of varying degrees of knee flexion contracture. We conducted a retrospective cohort study of patients undergoing primary TKA by a single surgeon between January 2023 and June 2024. Patients were categorized into three groups according to preoperative knee flexion contracture severity: Group A (mild, ≤ 15°, 40 knees), Group B (moderate, 15°–30°, 35 knees), and Group C (severe, > 30°, 28 knees). Coronal plane varus deformity was assessed using the Giles classification for baseline characterization. All procedures utilized the Smith & Nephew Brainlab 3.0 navigation system with posterior-stabilized implants and measured resection technique.We recorded operative duration, blood loss, bone resection volume, alignment accuracy, and sequential flexion contracture correction data.Preoperative and final FU assessments included Visual Analog Scale(VAS)pain scores, Knee Society Score(KSS), range of motion(ROM), and complications. The study included 103 knees.Postoperative hip-knee-ankle(HKA)angles were restored to the ideal range of 180°±3° across all groups(<i>P</i> > 0.05).Group C demonstrated significantly longer operative times (126.7 ± 15.3 min), greater intraoperative blood loss(372.8 ± 70.5 mL), and higher rates of posterior capsular release(92.9%)compared to Groups A and B(<i>P</i> < 0.001).During flexion contracture correction, residual flexion angles after trial implantation in Group C measured 9.2°±3.5°,decreasing to 2.8°±2.1° following targeted release.At final FU, all groups showed significant improvements in VAS scores, KSS, and ROM from preoperative values(<i>P</i> < 0.001),with no significant differences observed among the three groups(<i>P</i> > 0.05). Computer-navigated TKA enables precise correction of knee flexion contracture across severity levels.For severe deformities, the data-guided approach facilitates accurate bone resection and quantified soft tissue balancing, effectively addressing surgical challenges while achieving complete correction.Patients with severe deformities achieved early functional outcomes comparable to those with mild or moderate deformities.