Effect of Ankle-Foot Orthosis Alignment and Foot-Plate Length on the Gait of Adults With Poststroke Hemiplegia

Objective: To investigate the effect of ankle-foot orthosis (AFO) alignment and foot-plate length on sagittal plane knee kinematics and kinetics during gait in adults with poststroke hemiplegia. Design: Repeated measures, quasi-experimental study. Setting: Motion analysis laboratory. Participants: Volunteer sample of adults with poststroke hemiplegia (n= 16) and able-bodied adults (n= 12) of similar age. Interventions: Subjects with hemiplegia were measured walking with standardized footwear in 4 conditions: (1) no AFO (shoes only); (2) articulated AFO with 90 degrees plantar flexion stop and full-length foot-plate-conventionally aligned AFO (CAFO); (3) the same AFO realigned with the tibia vertical in the shoe-heel-height compensated AFO (HHCAFO); and (4) the same AFO (tibia vertical) with 3/4 length foot-plate-3/4 AFO. Gait of able-bodied control subjects was measured on a single occasion to provide a normal reference. Main Outcome Measures: Sagittal plane ankle and knee kinematics and kinetics. Results: In adults with hemiplegia, walking speed was unaffected by the different conditions (P=.095). Compared with the no AFO condition, all AFOs decreased plantar flexion at initial contact and mid-swing (P<.001) and changed the peak knee moment in early stance from flexor to extensor (P<.000). Both AFOs with full-length foot-plates significantly increased the peak stance phase plantar flexor moment compared with no AFO and resulted in a peak knee extensor moment in early stance that was significantly greater than control subjects, whereas the AFO with three-quarter length foot-plate resulted in ankle dorsiflexion during stance and swing that was significantly less than control subjects. Conclusions: These findings suggest that when an articulated AFO is to be used, a full-length foot-plate in conjunction with a plantar flexion stop may be considered to improve early stance knee moments for people with poststroke hemiplegia.