Effects of ankle-foot orthoses on ankle and foot kinematics in patients with subtalar osteoarthritis

Objective: To determine whether different foot orthoses have a similar effect on foot kinematics in subjects wit subtalar osteoarthritis (OA) when walking on various ground conditions. Design: Within-subject comparison study. Setting: Biomechanics research laboratory. Participants: Ten subjects with unilateral subtalar OA. Interventions: Custom-made ankle foot orthosis (AFO), rigid hindfoot orthosis (HFO-R), and articulated hindfoot orthosis (HFO-A) were used by subjects walking on level, ascending, and descending ramp, and side slope conditions. Main Outcome Measures: The triplanar range of motion of the calcaneus relative to tibia (hindfoot) and metatarsal relative to calcaneus (forefoot) was measured using an 8-camera motion analysis system when subjects with subtalar OA wore different foot orthoses. Results: Braces tended to perform similarly in reducing motion of the forefoot and hindfoot for all ground conditions when compared with unbraced but wearing shoes. The AFO significantly restricted frontal plane hindfoot motion during ramp descent (P<.Ol) and on a side slope when the arthritic subtalar joint was higher than the unaffected side (P=.02). The HFO-A provided significant frontal plane hindfoot motion restriction during ramp descent (P<.Ol) and on a side slope when the arthritic subtalar joint was lower than the unaffected side (P=.03). The HFO-R significantly restricted frontal plane hindfoot motion in all ground conditions except ramp ascent (P<.05). Conclusions: The HFO-R provides significant subtalar joint motion restriction while walking. The HFO-R may be considered an optimal orthosis for patients with subtalar OA pain arising from subtalar motion.