Muscle architecture and its relationship with lower extremity muscle strength in multiple sclerosis

This study was planned to determine the muscle architecture (pennation angle, muscle fiber length, and muscle thickness) and its relationship to lower extremity muscle strength in patients with Multiple Sclerosis (pwMS). The muscle architecture (pennation angle, muscle fiber length, and muscle thickness) and lower extremity muscle strength were assessed in 33 pwMS [13 Relapsing–Remitting MS (RRMS), 5 Primary Progressive MS (PPMS), 5 Secondary Progressive MS (SPMS), and 11 matched healthy controls (HC)]. Muscle architecture features were assessed with ultrasonography and muscle strength were assessed with a digital hand-held dynamometer. The rectus femoris muscle thickness and pennation angle, gastrocnemius muscle thickness, and the tibialis anterior pennation angle were significantly lower in pwMS compared to HC (p < 0.05). The strength of hip flexors, hip extensors, knee extensors, foot plantar, and foot dorsi flexors were lower in pwMS. In PPMS group, muscle strength of hip flexors was lower than RRMS and SPMS groups, and muscle strength of foot dorsi flexors was lower than RRMS (p < 0.05). In pwMS, positive correlations were found, between knee flexor strength and biceps femoris pennation angle. Also knee extensor strength and rectus femoris fiber length and muscle thickness were correlated positively (p < 0.05). According to our results the muscle architecture is affected in MS. The determination of architectural changes of lower extremity muscles may guide the arrangement of optimal strength exercises in functional rehabilitation programs.