Crouched posture maximizes ground reaction forces generated by muscles

Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for children with cerebral palsy; however, a crouched posture may allow biomechanical advantages that lead some children to adopt a crouch gait. To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle for a total of 45 different postures. A series of optimizations was performed for each posture to maximize transverse plane ground reaction forces in the eight compass directions by modifying muscle forces acting on the model. We compared the force profile areas across all postures. Larger force profile areas were allowed by postures from mild crouch (for initial stance) to crouch (for final stance). The overall ability to generate larger ground reaction force profiles represents a mechanical advantage of a crouched posture. This increase in muscle capacity while in a crouched posture may allow a patient to generate new movements to compensate for impairments associated with cerebral palsy, such as motor control deficits.

► We used musculoskeletal modeling and optimization to investigate one possible advantage to crouch gait. ► We placed an OpenSim gait model in 45 different postures from upright to crouch during the stance phase. ► We maximized horizontal ground reaction forces in eight compass directions (e.g., force profile) by adjusting muscle forces. ► The largest force profile areas were found for postures from mild crouch (in initial stance) to crouch (in final stance). ► The ability to generate large force profiles represents a mechanical advantage of adopting a crouched posture.