Impact of Wrist and Finger Extension on Passive Joint Torques and Their Association with Forearm Flexor Muscle...

This study aimed to characterize interlimb differences in passive torques (PT) at the wrist and metacarpophalangeal (MCP) joints in individuals with hemiparetic cerebral palsy (HCP), and to relate them to previously acquired diffusion tensor imaging (DTI)-derived diffusivity measures in forearm flexor muscles. In 10 individuals (5F, 18.14±8.7 years) with HCP, a custom-built device was used to measure the PTs produced by the wrist and MCP joints of both limbs in 16 discrete hand configurations. Interlimb differences in wrist and finger PT showed significant increases with extreme wrist and finger extension and severity of HCP. Furthermore, increased interlimb differences in PT during extreme wrist and finger extension were significantly correlated with DTI-derived diffusivity estimates, indicating that underlying structural muscle changes are related to increased PTs in extended hand configurations.Clinical Relevance- These findings establish that intrinsic forearm muscle adaptations significantly and negatively influence passive biomechanical properties when individuals with HCP extend their wrist/fingers to the end of their passive range of motion.