Science News: Comparing the Effect of Implanted Peroneal Nerve Stimulation and Ankle-Foot Orthosis on Gait Kinematics in Chronic Hemiparesis: A Randomized Controlled Trial

Citation: Hutin E, Ghédira M, Vinti M, Tazi S, Gracies JM, Decq P. Comparing the effect of implanted peroneal nerve stimulation and ankle-foot orthosis on gait kinematics in chronic hemiparesis: A randomized controlled trial. J Rehabil Med. 2023;55:jrm7130. Published 2023 Aug 7. doi:10.2340/jrm.v55.7130

Summary: Following a central nervous system (CNS) insult, the resulting spastic gait pattern is often characterized by impaired dorsiflexion. This limitation is most noticeable during the swing phase, resulting in reduced foot clearance, posing an increased tripping hazard, and decreased efficiency. Multiple factors are believed to contribute, including dorsiflexor weakness, plantar flexor spasticity, and co-contraction dyssynergy. Traditionally, this has been corrected with ankle foot orthotic (AFO) that passively positions the ankle in neutral and only works to address the latter two factors. The study at hand investigated the effects of semi-implanted selective functional electrical stimulation (SIS-FES) on gait kinematics compared to AFOs. In a controlled study, participants (n=27) were randomized to either the AFO or SIS-FES group. Subjects were required to have passive dorsiflexion to a neutral position and be able to ambulate a minimum of 50 meters with or without an assistive device. Gait mechanics were recorded two months before device implantation of a STIMuSTEP or AFO fitting and again at three and six months. At each assessment, three sets of measurements were collected with a stimulator or AFO off, then on, and finally off again. The primary outcome was walking speed, but due to multiple secondary outcomes, a Bonferroni correction factor was used. At the three-month follow-up, there was a non-significant difference between groups after turning on stimulation or donning AFOs in terms of walking speed, cadence, bilateral step length, ankle dorsiflexion amplitude, and knee flexion amplitude (p>0.05). There was, however, a significant decrease in mean dorsiflexion speed after taking off the AFO that was not observed in the SIS-FES group (AFO: OFF, 11.4±9.1°/s, ON, 4.6± 4.7°/s, p = 0.02; SIS-FES: OFF, 13.9 ± 8.8°/s, ON, 13.7± 8.8°, p>0.05). The impact of training was evaluated by comparing gait kinematics at three and six months while subjects used their AFO or with SIS-FES turned on. No significant difference was observed between groups or over time (all p>0.05). The therapeutic benefit was evaluated by comparing gait mechanics before implantation or AFO fitting and again at three and six months without using the respective devices. While there was a significant increase in maximal knee flexion, it was only 2 (p=0.03), and no significant difference was seen between groups. (p>0.05). The overall impact of device use was evaluated by comparing gait kinematics at baseline to those at six months while using their respective devices. While SIS-FES showed significant speed increases (+0.10 m/s, p=0.03), cadence (+0.09 steps/s, p=0.006), maximum dorsiflexion (+5, p=0.0002) and mean knee flexion speed (+11/s, p=0.04); there was no significant difference when compared to those with AFOs.