Muscle Activation and AFOs
A recent study looked closely at muscle activation and AFOs (ankle foot orthotics). The researchers explored how AFOs affect muscle activity during walking in the lower leg and ankle. Pediatric physical therapists frequently work on gait training with children who have cerebral palsy and use orthotics. The results of the study may be helpful in choosing the correct style of AFO depending upon the client’s goals.
Methodology of the Study
The study was a repeated-measures trial where electromyographic activity in medial gastrocnemius and tibialis anterior was recorded from 17 children (average age: 8.4 years ± 1.3 years) with spastic unilateral cerebral palsy.
The EMG activity was recorded when the children were walking barefoot and with two designs of a custom-made hinged ankle-foot orthosis with:
- unmodified, flatter footplates
- rectified, contoured footplates.
Data was collected on total muscle activity and relative change in profiles of muscle activity.
Results of the Study on Muscle Activation and AFOs
Data analysis revealed the following:
- no statistical difference was found in total activity of either muscle for the ankle-foot orthosis with an unmodified footplate.
- a significant reduction in muscle activity of tibialis anterior was seen for the ankle-foot orthosis with a contoured footplate compared to barefoot walking.
- Profiles of change in muscle activity were significantly different for both shank muscles between all walking conditions.
- the greatest differences were decreased activity in medial gastrocnemius during early stance phase and lower activity in tibialis anterior during swing phase with orthotic devices.
Therapeutic Play Activities for Children
Conclusion
The researchers concluded that orthotic management with hinged ankle-foot orthoses may decrease spastic activation of medial gastrocnemius in children with spastic unilateral cerebral palsy in addition to functionally inactivating tibialis anterior during gait. The hinged ankle-foot orthosis with an unmodified footplate resulted in better performance by facilitating more functional muscle activity in the tibialis anterior while preventing a spastic response in the medial gastrocnemius muscle.
Reference: Lindskov, L., Huse, A. B., Johansson, M., & Nygård, S. (2020). Muscle activity in children with spastic unilateral cerebral palsy when walking with ankle-foot orthoses: an explorative study. Gait & Posture, 80, 31-36.
