‘Russell and Gorter reply’

Abstract

'Assessing functional differences in gross motor skills in children with cerebral palsy who use an ambulatory aid or orthoses: can the GMFM-88 help?' SIR-We read with interest the article by Russell and Gorter 1 recently published in this journal. The authors reported on the sensitivity of the 88-item Gross Motor Function Measure (GMFM-88) to detect within-child changes in function between aided (walking aids and orthoses) and barefoot walking conditions. In the introductory section of their article, Russell and Gorter reviewed one of our studies 2 with children with cerebral palsy where we looked at the effect of wearing hinged ankle-foot orthoses (AFOs) on gross motor function related to walking (the Standing and the Walking, Running and Jumping dimensions of the GMFM-88) and on the oxygen cost of treadmill walking. Russell and Gorter rightly stated that we found that wearing AFOs resulted in a decrease in the oxygen cost of walking but did not affect GMFM scores. We collected data when participants wore their AFOs and shoes and when they wore shoes only. Russell and Gorter, however, incorrectly described our second condition as barefoot. We wish to bring this error to the attention of the readers of this journal for two reasons. First, our results show that oxygen uptake (at least during treadmill walking), is sensitive to changes related to wearing AFOs compared with wearing shoes. This is in contrast to studies on the effects of AFOs on gait biomechanics. As Russell and Gorter point out, such studies have found that biomechanic changes are 'less discernible' when the control condition is walking in shoes compared with when it is walking barefoot. Indeed, in some cases there is no change in biomechanic variables when children wear their AFOs and shoes compared with when they wear their shoes alone. 3 Second, although not made explicit by Russell and Gorter, it would be inappropriate to conclude that our finding of no AFO-related differences in the GMFM scores for the Walking, Running and Jumping dimension directly contrasts their results. While they did find that for their participants at Gross Motor Function Classification System Level I (similar in function to our own participants) wearing AFOs resulted in an increase in GMFM scores for this same dimension, their participants were barefoot for the control condition unlike in our study, where the participants wore their shoes.