General discussion
8.6. General conclusions
• Spasticity can be recognized during gait in children with cerebral palsy:
Ͳ Spastic muscles are stretched slower during gait than non-spastic muscles and reach shorter peak lengths, even when controlling for walking speed.
Ͳ An increased coupling exists between stretch velocity and muscle activity in spastic muscles during gait, which increases with walking speed.
• To investigate the effect of spasticity during gait of (individual) patients, muscle-tendon stretch velocity and muscle activity, as well as the coupling between the two should be assessed.
• Muscle contractures mainly affect the (peak) length at which a muscle operates during gait, but not the velocity with which it is stretched.
• Walking speed affects muscle-tendon length and velocity, as well as joint kinematics and gait classifications. The worsening of gait deviations with walking speed can (partly) be attributed to the velocity-dependent effect of spasticity, and may limit comfortable walking speed. Therefore, walking speed is important to consider when analyzing gait data.
• Dynamic effects of a crouched pattern lead to reduced knee flexion in swing. Dynamic effects are important to consider as possible causes of gait deviations, next to abnormal local muscle functioning.
• Musculoskeletal modeling gives insight into the role of impairments during gait, especially when impairments lay at the muscle or muscle-tendon level. The use of musculoskeletal modeling is recommended to assist in clinical decision making and treatment evaluation, for example in the case of spasticity treatment and muscle-lengthening surgery.
• Further study using forward dynamic modeling techniques is recommended, to gain a better understanding of cause and effect relationships between impairments and gait deviations that are difficult to prove with experimental studies alone.
127
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