Use of orthoses lowers the O-2 cost of walking in children with spastic cerebral palsy

Purpose: The aim of this study was to assess the effects of hinged ankle fo ot orthoses (AFO) on the metabolic and cardiopulmonary cost of walking and gross motor skills of children with cerebral palsy (CP). Methods: Ten habit ual users of hinged AFO with spastic diplegic CP (9.01 yr +/- 2.10) partici pated in the study. Expired gas and heart rate (HR) were measured during si tting and with AFO on and off during steady state treadmill walking at thre e speeds: 3 km . h(-1), comfortable walking speed (CWS), and 90% of their f astest walking speed (FWS). Comfortable and fastest ground walking speed an d Gross Motor Function Measure scores were also assessed with AFO on and of f and analyzed with ANOVA. Because not all children could walk at all speed s on the treadmill, an ANOVA was performed on data for children who walked at 3 km . h(-1) and CWS (N = 8 for HR; N = 9 for pulmonary ventilation and metabolic variables) and a t-test on data at 90% of FWS (N = 9 for HR; N = 8 for pulmonary ventilation and metabolic variables). Results: When childre n wore their AFO net oxygen uptake (L.min(-1), absolute - sitting values) w as significantly (P < 0.05) reduced by 8.9% at 3 km .h(-1) and by 5.9% at 9 0% of FWS. Net pulmonary ventilation (L.min(-1)) was significantly (P < 0.0 5) lower with AFO on by 10.3% but only at 3 km.h(-1). AFO did not affect ne t HR (beats.min(-1)) nor the respiratory exchange ratio at any speed, nor a ny physiologic variable at CWS, nor gross motor skills. Conclusions: Use of hinged AFO reduces the oxygen and ventilatory cost of walking in children with spastic diplegic CP.