Roles of Reflex Activity and Co-contraction During Assessments of Spasticity of the Knee Flexor and Knee Extensor Muscles in Children With Cerebral Palsy and Different Functional Levels

Pierce S, Barbe M, Barr A, Shewokis P, Lauer R

A common clinical feature of Cerebral Palsy (CP) is spasticity, which impacts the level of achievable functional activity. This study aimed to assess spasticity of both knee flexors and extensors in children with CP, focusing on differences in passive resistive torque, reflex activity, co-activation and reciprocal facilitation.  

The study group consisted of 20 children with CP, which were further divided into two subgroups using the Gross Motor Function Classification Scale (GMFCS)
An isokinetic dynamometer and electromyography of vastus lateralis and medial hamstring muscles was used to assess the previously stated variables during passive knee flexion through various ranges.

The study concluded that children with CP demonstrate more knee flexor spasticity than children with ‘typical development’. However, results showed that in some children with CP there was an increase in reflex activity with no increase in torque, suggesting that reflex activity plays a less important role in spasticity.

Physical Therapy, 2008, 88(10), 1124-1134

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