Original article
Center of Mass Movement and Energy Transfer During Walking in Children With Cerebral Palsy

Presented in part to the North American Society for the Psychology of Sport and Physical Activity Meeting, June 10–12, 2004, Vancouver, BC.
https://doi.org/10.1016/j.apmr.2005.05.012Get rights and content

Abstract

Bennett BC, Abel MF, Wolovick A, Franklin T, Allaire PE, Kerrigan DC. Center of mass movement and energy transfer during walking in children with cerebral palsy.

Objective

To gain insight into the mechanical inefficiencies of gait patterns used by children with spastic diplegia by analysis of center of mass (COM) movement and energy recovery.

Design

Prospective study using between-group measures to analyze differences between children with cerebral palsy (CP) and age-matched controls without CP.

Setting

Assessments were performed in a gait laboratory.

Participants

Fifteen children with spastic diplegia and 6 age-matched controls without CP with a mean age of 9.7 years.

Interventions

Not applicable.

Main Outcome Measures

Gait data assessed included temporal-distance factors, COM vertical excursion, work done on the COM, and the percentage of energy transferred and relative phase between the potential and kinetic energy.

Results

Children with CP had a 33% smaller energy recovery factor than the controls (P<.001). They also had 60% greater COM vertical excursion (P<.02) and a poorer phasic relation between potential and kinetic energies (P<.02), both of which contributed to greater mechanical work performed (P<.003).

Conclusions

Compared with the age-matched controls without CP, the children with CP were mechanically less efficient in their gait. Interventions that promote heel contact and roll over and greater knee stability to better utilize the kinetic energy of push-off could improve walking efficiency.

Section snippets

Participants and Procedures

Data were collected on a convenience sample of 15 children with spastic diplegic CP and 6 age-matched controls without CP. Subjects with CP were generally community ambulators, with a mean score of 92% on the Gross Motor Function Measure (GMFM)14 and walked without aids. Subject anthropometrics are summarized in table 1. None of the subjects had undergone surgery or other significant treatments within the last 6 months. All tests were conducted in the Motion Analysis and Motor Performance

Results

The results of this study supported our hypotheses and are summarized in table 2. The vertical excursion of the normalized COM was 80% of the compass gait model’s excursion for the children with CP, but only 51% of this value in the control group. There was no difference in the lateral movement of the COM between controls and the group with CP. The children with CP had shorter strides but their preferred walking speed was not significantly slower because they had increased cadence, which

Discussion

The results of this study support our hypothesis that the gait of children with CP is less pendular than that of the controls. An ideal pendulum has PE and KE curves that are equal in amplitude, 180° out of phase, and sinewaves. We found the COM energy curves of the group with CP lacking in all 3 measures. The increased vertical excursion of the group with CP meant that there was greater variation in PE than KE during the gait cycle. The lack of symmetry of the gait, the nonsinusoidal

Conclusions

This study has shown that the use of COM parameters provides insights that can aid kinematic analysis and can be applied to the gait patterns of an individual patient to either guide or evaluate interventions. The analysis can show when energy recovery is or is not possible and estimate the improvement in mechanical work resulting from a specific change in the gait pattern. Although each patient is unique, the COM dynamics in the subjects with CP showed significant deviations from normal,

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    Supported by the National Institutes of Health (grant no. 5R24HD039631) and the Pediatric Orthopaedic Society of North America.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

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