Potential Instability and Malfunction of Knee Joints with Vastus Medialis Impairment after Total Knee Arthroplasty

Do Preoperative Vastus Medialis Volume and Quality Affect Functional Outcomes after Total Knee Arthroplasty?

Background: Vastus medialis function has been implicated in the development and progression of knee osteoarthritis; however, studies evaluating the influence of its preoperative volume and quality on functional outcomes following total knee arthroplasty (TKA) remain scarce. This study aimed to determine the association between vastus medialis volume, quality, and clinical outcomes after TKA. Methods: Among the patients who underwent unilateral TKA, 92 who had undergone magnetic resonance imaging (MRI) before TKA were included. Preoperative vastus medialis volume and quality were assessed using the cross-sectional area (CSA) and fat infiltration ratio on MRI. Clinical outcomes were evaluated using the Knee Society knee score (KSKS) and Knee Society function score (KSFS) at baseline and 1 year after surgery. The relationships between preoperative CSA, fatty infiltration ratio, and clinical outcomes were analyzed using univariate and multivariate linear regression. Results: Only the fatty infiltration ratio was significantly associated with postoperative KSFS in the univariate linear regression analysis. In the multivariate linear regression analysis, age and fatty infiltration ratio were significantly associated with postoperative KSFS. Conclusions: Increased vastus medialis fat infiltration is associated with worse functional outcomes after TKA. Preserving vastus medialis quality could improve functional outcomes, and surgeons should encourage patients to perform quadriceps strengthening exercises before surgery.