Effects of ankle-foot orthoses on ankle and foot kinematics in patient with ankle osteoarthritis.

OBJECTIVE: To determine if different foot orthoses have a similar effect on foot kinematics in subjects with ankle osteoarthritis (OA) when walking on various ground conditions.

DESIGN: Within-subject comparisons study.

SETTING: Biomechanics research laboratory.

PARTICIPANTS: Thirteen subjects with unilateral ankle OA.

INTERVENTIONS: Custom-made ankle-foot orthosis (AFO), rigid hindfoot orthosis (HFO-R), and articulated hindfoot orthosis (HFO-A) were used by subjects when walking on level, ascending and descending ramp, and side-slope conditions.

MAIN OUTCOME MEASURES: The range of motion of the hindfoot (calcaneus relative to tibia) and forefoot (metatarsal relative to calcaneus) was measured using an 8-camera motion analysis system.

RESULTS: The AFO and HFO-R provided the best sagittal plane hindfoot motion restriction over all ground conditions (P<.001). The HFO-R allowed the greatest sagittal plane forefoot motion when walking over level (P=.01) and side-slope (P<.02) conditions, the greatest frontal plane forefoot motion walking down the ramp (P=.003), and the greatest transverse plane forefoot motion when walking over level (P=.011) and ramp-ascending conditions (P=.005). The HFO-A restricted motion of the unaffected joint and did not effectively restrict hindfoot motion.

CONCLUSIONS: The HFO-R not only provides selective restriction to the ankle-hindfoot motion, but also allows sufficient forefoot motion compared with the AFO. We consider the HFO-R to be the best option of all tested orthoses for treating patients with ankle OA pain arising from ankle motion.