Understanding muscle energy expenditure variations following selective dorsal rhizotomy while maintaining consistent energy consumption

Increased energy demands during walking is a recurrent issue for children with cerebral palsy (CP). Given the high incidence of spasticity in these children, several authors have analyzed the impact of selective dorsal rhizotomy (SDR) on energy consumption during walking, typically showing minimal changes post-SDR. To further investigate muscle behavior after SDR, our recent study identified alterations in individual muscle force production without changes in muscle activation during walking. This suggests that children with CP may experience a more favorable dynamic scenario for developing sub-maximal muscle forces after SDR, due to reduced spasticity unlocking joint movement. Thus, this raises questions about whether these changes in muscle force production could lead to increased muscle energy expenditure, which may not be fully reflected in overall energy consumption.

The aim of this study was to build upon our previous research on muscle behavior after SDR by evaluating the surgery’s impact on individual muscle energy expenditure during walking, using neuro-musculoskeletal simulations. Our research compared two matched groups comprising 81 children with CP: those who underwent SDR and those who did not.

Our results showed no significant changes in overall energy consumption or total muscle energy expenditure in either group post-surgery. However, we observed alterations in individual muscle energy expenditure during walking in the SDR group compared to children with CP who received other treatments. Compared to the findings from our first study, we observed a significant decrease in spasticity of the plantarflexor muscles, an improvement in ankle joint angle, an increase in individual muscle force during walking, and no statistically significant changes in energy expenditure of the gastrocnemius and soleus muscles post-SDR. These findings, along with the absence of changes in muscle activity post-SDR, support the hypothesis that muscle tissue alterations contribute to energy deficits observed in children with CP during walking.