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Muscle activity in children with spastic unilateral cerebral palsy when walking with ankle-foot orthoses: an
Lærke Lindskov1, Ann-Britt Huse1, Marie Johansson2
1Motion Analysis Laboratory, Oslo University Hospital - Rikshospitalet, Sognsvannsveien 20, 0372 Oslo, Norway; Sophies Minde Ortopedi AS, Brynsveien 14, 0667 Oslo, Norway.
Insights
Hinged ankle-foot orthoses may reduce medial gastrocnemius spasticity in children with cerebral palsy. However, they can also decrease tibialis anterior activity, with flatter footplates showing better gait function outcomes.
Area of Science:
- Orthopedics
- Pediatric Rehabilitation
- Biomechanics
Background:
- Spastic unilateral cerebral palsy (CP) often causes equinus gait in children.
- Hinged ankle-foot orthoses (HAFOs) are used to improve gait but their effect on muscle activity is not well understood.
Purpose of the Study:
- To investigate the impact of two HAFO footplate designs on medial gastrocnemius and tibialis anterior muscle activity during gait in children with spastic unilateral CP.
Main Methods:
- A prospective, repeated-measures trial involving 17 children with spastic unilateral CP.
- Electromyography recorded muscle activity during barefoot walking and with two HAFO designs: unmodified (flatter) and rectified (contoured) footplates.
- Outcomes included total muscle activity and changes in muscle activity profiles.
Main Results:
- No significant difference in total muscle activity for either muscle with the unmodified footplate HAFO.
- A contoured footplate HAFO significantly reduced tibialis anterior activity compared to barefoot walking.
- Both HAFO designs altered muscle activity profiles, decreasing medial gastrocnemius activity in early stance and tibialis anterior activity in swing.
Conclusions:
- HAFOs may reduce medial gastrocnemius spasticity in children with CP.
- Contoured footplate HAFOs might lead to functional inactivation of the tibialis anterior during gait.
- The unmodified footplate HAFO demonstrated better performance by promoting more functional muscle activity while controlling spasticity.
Background:
A hinged ankle-foot orthosis is prescribed for children with spastic unilateral cerebral palsy to improve gait function by correcting spastic equinus. However, little is known about how orthotic management relates to muscle activity during walking in this population.
Research Question:
Does muscle activity in medial gastrocnemius and tibialis anterior change in children with spastic unilateral cerebral palsy when walking with hinged ankle-foot orthoses featuring two different footplate designs?
Methods:
In this prospective, repeated-measures trial, electromyographic activity in medial gastrocnemius and tibialis anterior was recorded from 17 children (mean age: 8.4 years ± 1.3 years) with spastic unilateral cerebral palsy walking barefoot and with two designs of hinged ankle-foot orthosis. The orthotic devices consisted of custom-made hinged ankle-foot orthoses with unmodified, flatter footplates and rectified, contoured footplates. Primary outcome measures were total muscle activity, quantified as the area under a linear envelope, and relative change in profiles of muscle activity, depicted by curves of mean difference with 95% confidence bands.
Results:
No statistical difference was found in total activity of either muscle for the ankle-foot orthosis with an unmodified footplate but a significant reduction in muscle activity of tibialis anterior was seen for the ankle-foot orthosis with a contoured footplate relative to barefoot walking. Profiles of change in muscle activity were significantly altered for both shank muscles between all walking conditions. The most pronounced differences were decreased activity in medial gastrocnemius during early stance phase and lower activity in tibialis anterior during swing phase with orthotic devices.
Significance:
Orthotic management with hinged ankle-foot orthoses may mitigate spastic activation of medial gastrocnemius in children with spastic unilateral cerebral palsy but also appears to functionally inactivate tibialis anterior during gait. The hinged ankle-foot orthosis with an unmodified footplate corresponded with better performance by facilitating more functional muscle activity while impeding spastic response.
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