I’m in the middle of a couple projects right now and in working on those, I came across this article. I’ve seen functional electrical stimulation (FES) used to manage foot drop, although not used it much myself. It’s been too time consuming to set-up and also, I have a bit of a tech allergy honestly; I’m awesome at making tech break. But beyond that, folk don’t typically come to inpatient rehab with just foot drop; they always have more complicated gait problems. One issue I see a lot is knee hyperextension in gait. This study is looking at using FES to correct knee hyperextension in particular.
The patient in this case study was 51 years old man about a year post stroke. He was complaining of severe pain when he was walking in his knee and exhibited knee hyperextension in stance with an absence of further gait troubles. Upon observation, it was determined that the cause of the knee hyperextension was due to limited ankle dorsiflexion in stance, which in turn limited the tibia’s ability to advance. He didn’t like the idea of an AFO. They tried botulism injections to the plantarflexors to decrease their spasticity, but this was unsuccessful. So they tried external FES stimulation of the peroneal nerve and had good success. BUT the external control box prevented him from being able to kneel at work. (He worked in construction.) So, they went with an implantable FES. To quantifiably measure gait before and after implantation, they used a clinical gait analysis motion capture system with video to “compute 3-dimensional kinematics, kinetics and ground reaction forces.”
After implantation, the patient was placed in a knee extension splint for 3 weeks, so that movement would not disrupt the wiring as it healed and integrated into the body. After those 3 weeks, the FES was activated and training began. The training program included 1 hour 4 times a week educational sessions for a month as well as a 3 month gait rehab program of 1 hour sessions, 3 times a week focusing on optimal use of the FES device (how to adjust it, turn on/off, etc.), gait symmetry and knee control (“ie quadriceps strengthening with eccentric contraction exercises such as going down stairs and knee flexion management with exercises such as flexed knee gait”).
After treatment was completed they re-did the gait analysis and found that their hypotheses were confirmed: “(1) that the FES would improve ankle dorsiflexion at initial contact by generating stimulation-induced contraction of the dorsiflexors during the swing phase and (2) that extension of the stimulation into the loading phase should ensure a tibial advancement and thus reduce knee hyperextension.” They were able to achieve the second, by setting a 0.2ms ramp up/down time on the stimulation.
More importantly, the patient was satisfied with the results.
One thing that stuck out to me is that this person was basically the perfect candidate for this study. He was fairly young, motivated to return to work and had a fairly uncomplicated gait deficit. So, this may not be appropriate in more complicated cases. BUT like I always say, “never hurts to try!”