Kinematic and kinetic benefits of implantable peroneal nerve stimulation in people with post-stroke drop foot using an ankle-foot orthosis.
BACKGROUND
Contralesional 'drop foot' after stroke is usually treated with an ankle-foot orthosis (AFO). However, AFOs may hamper ankle motion during stance. Peroneal functional electrical stimulation (FES) is an alternative treatment that provides active dorsiflexion and allows normal ankle motion. Despite this theoretical advantage of FES, the kinematic and kinetic differences between AFO and FES have been scarcely investigated.


OBJECTIVE
To test whether walking with implanted FES leads to improvements in stance stability, propulsion, and swing initiation compared to AFO.


METHODS
A 4-channel peroneal nerve stimulator (ActiGait ®) was implanted in 22 chronic patients after stroke. Instrumented gait analyses were performed during comfortable walking up to 26 weeks (n = 10) or 52 weeks (n = 12) after FES-system activation. Kinematics of knee and ankle (stance and swing phase) and kinetics (stance phase) of gait were determined, besides spatiotemporal parameters. Finally, we determined whether differences between devices regarding late stance kine(ma)tics correlated with those regarding the swing phase.


RESULTS
In mid-stance, knee stability improved as the peak knee extension velocity was lower with FES (β = 18.1°/s, p = 0.007), while peak ankle plantarflexion velocity (β = -29.2°/s, p = 0.006) and peak ankle plantarflexion power (β = -0.2 W/kg, p = 0.018) were higher with FES compared to AFO. With FES, the ground reaction force (GRF) vector at peak ankle power (i.e., 'propulsion') was oriented more anteriorly (β = -1.1°, p = 0.001). Similarly, the horizontal GRF (β = -0.8% body mass, p = 0.003) and gait speed (β = 0.03 m/s, p = 0.015) were higher. An increase in peak ankle plantarflexion velocity and a more forward oriented GRF angle during late stance were moderately associated with an increase in hip flexion velocity during initial swing (rs = 0.502, p = 0.029 and rs = 0.504, p = 0.028, respectively).


CONCLUSIONS
This study substantiates the evidence that implantable peroneal FES as a treatment for post-stroke drop foot may be superior over AFO in terms of knee stability, ankle plantarflexion power, and propulsion.
['Berenpas|Frank|F|', 'Schiemanck|Sven|S|', 'Beelen|Anita|A|', 'Nollet|Frans|F|', 'Weerdesteyn|Vivian|V|', 'Geurts|Alexander|A|']
D000328:Adult D000368:Aged D000843:Ankle Joint D001696:Biomechanical Phenomena D015331:Cohort Studies D004599:Electric Stimulation Therapy D005260:Female D061826:Foot Orthoses D020233:Gait Disorders, Neurologic D006801:Humans D007717:Knee D008297:Male D008875:Middle Aged D010543:Peroneal Nerve D020521:Stroke D000071939:Stroke Rehabilitation D016896:Treatment Outcome
peroneal nerve ankle-foot orthosis stroke Functional electrical stimulation gait rehabilitation