The Role of Muscle Architecture as a Determinant of Functional Performance in Women With Knee Osteoarthritis

Background and Purpose: Knee osteoarthritis (KOA) is associated with early muscular alterations and muscle weakness, which contribute to disease progression. However, limited knowledge exists regarding the potential exacerbation of lower extremity muscle architecture and its impact on functional performance. This study aimed to investigate the relationship between knee extensor and ankle plantar flexor muscle architecture, femoral cartilage thickness, age, body mass index (BMI), pain severity, and functional performance in middle-aged women with KOA. Methods: A total of 87 patients diagnosed with KOA (mean age = 51.48 ± 4.89 years, mean BMI = 27.96 ± 4.66 kg/m2) were included in the study. Ultrasonography was used to assess muscle thickness, adipose tissue thickness, pennation angle, and the muscle/adipose tissue thickness ratio (MATR) of the Rectus Femoris (RF), Vastus Medialis (VM), Vastus Lateralis (VL), and Medial Gastrocnemius (MG) muscles. Physical performance was evaluated through the stair-climbing test and the 10-time sit to stand test. Pearson's correlation test and multiple linear regression analysis were used. Results: The pennation angle of the VL and pain level predicted sit to stand test results; the pennation angle of RF, age, BMI and pain level predicted stair-climbing test results (p < 0.001). Femoral cartilage thickness at the medial condyle, intercondylar area, and lateral condyle correlated with performance in both tests (p < 0.001). Additionally, age, BMI, pain intensity, muscle thickness, pennation angle and MATR of RF, VL, and VM correlated with both functional tests (p < 0.05). Discussion: Muscle architecture alterations correlated with functional test results in patients with KOA. Understanding the influence of muscle architecture on functional parameters can facilitate the development of effective rehabilitation strategies to preserve and optimize patient function before it becomes compromised. Trial Registration: Enrolled in clinical trials and awaiting approval.