Change of dynamic gastrocnemius and soleus muscle length after block of spastic calf muscle in cerebral palsy

Objective: The purpose of this study was to evaluate the efficacy of gastroonemius and soleus muscle length measured by gait analysis for characterizing the spastic calf muscles in ambulant cerebral palsy. Methods: A total of 20 limbs in the 16 children with diplegic or hemiplegic cerebral palsy showing spasticity of the calf muscle were analyzed by three-dimensional gait analysis before and after botulinum toxin injection. Results: The mean maximal ankle dorsiflexion angle, the minimal knee flexion angle in stance, and the dynamic gastrocnemius and soleus muscle lengths increased after the block. Paradoxically the dynamic gastrocnemius muscle lengths decreased in the eight patients after the block, all of whom had a common characteristic of the genu recurvaturn. In contrast, dynamic soleus length, knee angle, and ankle angle improved after the injection. Conclusion: Gastrocnemius length and soleus length are useful variables to evaluate the antispastic effect of botulinum toxin in patients with cerebral palsy. When the genu recurvatum is present, the soleus muscle length is more informative than gastrocnemius length.