Functional and Radiological Results of the Subvastus Versus Medial Parapatellar Method in Total Knee Arthroplasty: A Randomized Controlled Cohort

Abstract

Abstract Introduction: The subvastus method preserves the quadriceps mechanism and may facilitate earlier recovery for total knee arthroplasty (TKA). This current trial evaluated functional, pain, and radiological outcomes between the subvastus and medial parapatellar methods. Materials and Methods: This randomized controlled trial included 100 patients with primary or secondary osteoarthritis who underwent TKA at a major medical center in India between July 2023 and September 2025. Patients were randomly allocated to either the subvastus method (n = 50) or the medial parapatellar method (n = 50). Pain was evaluated using the Visual Analog Scale (VAS), whereas functional recovery was measured based on range of motion (ROM) and Knee Society Scores (KSS). Radiological outcomes included component alignment and hip-knee-ankle (HKA) angle. Patients were followed for 6 months. Results: The subvastus group displayed substantially lower post-operative VAS scores during the first 3 days. ROM was significantly greater with the subvastus method at 2 weeks (82.56° ± 9.11° vs. 78.02° ± 7.33°; P = 0.007) and 6 weeks (98.14° ± 10.38° vs. 92.86° ± 5.20°; P = 0.002) but became comparable at 3 months. KSS improved progressively in both groups, with no significant difference at 6 months. Coronal and sagittal component alignment and HKA angles were comparable between groups. Post-operative complications were infrequent and similar between methods. Conclusion: The subvastus method was associated with improved early post-operative pain relief and ROM in comparison with the medial parapatellar method, whereas functional and radiological outcomes were comparable at later follow-up. These findings suggest that preservation of the extensor mechanism with the subvastus method may facilitate early post-operative recovery following TKA.