Evaluation of relationship between muscle architecture and muscle power of quadriceps, tibialis anterior and gastrocnemius muscles in female patients with gonarthrosis

Objective: The aim of this study is to investigate the relationship between the muscle architecture of muscles potentially affected in addition to the knee extensor muscles in patients with knee osteoarthritis (OA) and the isometric muscle strength measured by hand-held dynamometer in terms of isometric knee extension, ankle dorsiflexion, and plantarflexion, as well as functional parameters. Materials and Methods: Thirty female patients with unilateral stage 2 and above knee OA were included in the study. The knee without OA/painless and the knee with a lower stage compared to the affected side were taken as the control. Muscle architecture parameters, including muscle thickness (MT), pennation angle (PA) and fascicle length (FL) of Vastus lateralis (VL), Tibialis Anterior (TA), Gastrocnemius medial head (GKM) and lateral head (GKL) muscles were evaluated using ultrasound. Ultrasound assessment also included OMERACT Knee OA ultrasound scores. Isometric maximal and average muscle strengths, including knee extension, ankle plantarflexion and ankle dorsiflexion were measured using a hand-held dynamometer. Numeric Rating Scale (NRS), Western Ontario and McMaster Universities Osteoarthritis (WOMAC), and Health Assessment Questionnaire (HAQ) scales were used to assess pain and disability in patients. Results: Isometric maximal and average muscle strengths of knee extension, ankle plantarflexion and ankle dorsiflexion were significantly decreased on the affected side. Among the muscle architecture parameters, VL muscle MT and FL; TA muscle MT; GKL muscle MT and FL values were significantly decreased on the affected side, while no significant difference was observed in GKM muscle architecture parameters between the control and affected sides. Except for GKM muscle's PA, no significant relationship was found between the muscle architecture parameters of any muscle and the strength of the movement it is responsible for. No relationship was found between OMERACT Knee OA ultrasound scores and muscle strengths, while a relationship was found between synovitis sub-score and GKM muscle's MT and FL, and cartilage staging sub-score and GKM muscle's FL. Conclusion: In addition to knee muscles, there is significant muscle involvement in ankle muscles in knee OA, and a loss of strength is observed in ankle muscles as well. Muscle involvement due to OA can be evaluated through ultrasound muscle architecture assessment. However, muscle strength loss is not associated with changes in muscle architecture. Therefore, an assessment through muscle architecture will not provide insights into muscle strengths.