Lower Extremity Muscle Tendon Interaction Around Knee During Gait Among Adolescent Children with Cerebral Palsy with Varying Crouch Angle

Background Optimal management and surgical planning of severe bony deformities and muscle tendon unit contractures demands comprehensive evaluation of all structures including the dynamic muscle tendon length of all muscles around the joint during gait. Objectives Present study aimed to explore dynamic muscle-tendon length for all muscles around the knee joint along with pelvis, hip, and ankle joint kinematics among adolescent children with varying crouch angle. Methods Muscle-tendon length of 29 adolescent children with cerebral palsy with varying crouch angles was computed using a full-body musculo-skeletal model and expressed as a percentage of muscle-tendon length during walking compared to resting condition. Results Children with knee flexion angle greater than 25 degrees demonstrated lower anterior pelvic tilt and 11% greater muscle-tendon length of semimembranosus and biceps femoris during stance phase of gait compared to children with knee flexion angle less than 25 degrees and typically developing children (p < 0.01). Conclusions The findings of present study reported that routine bedside clinical evaluation in adolescent children with knee flexion angle greater than 25 degrees revealed moderate shortening of hamstring muscle in supine position. Whereas instrumented objective evaluation of gait demonstrated lengthened hamstring muscle and reduced hip extension and relatively lower anterior pelvic tilt. Therefore, it may be valuable to add objective assessment of dynamic muscle-tendon length to kinematics of all lower-extremity joint motion during gait, in order to understand the muscle-joint interactions; particularly in children with severe crouch and plan specific, tailor-made surgical and non-surgical interventions.