Predictive simulation of post-stroke gait with functional electrical stimulation.

Post-stroke patients present various gait abnormalities such as drop foot, stiff-knee gait (SKG), and knee hyperextension. Functional electrical stimulation (FES) improves drop foot gait although the mechanistic basis for this effect is not well understood. To answer this question, we evaluated the gait of a post-stroke patient walking with and without FES by inverse dynamics analysis and compared the results to an optimal control framework. The effect of FES and cause-effect relationship of changes in knee and ankle muscle strength were investigated; personalized muscle-tendon parameters allowed the prediction of pathologic gait. We also predicted healthy gait patterns at different speeds to simulate the subject walking without impairment. The passive moment of the knee played an important role in the estimation of muscle force with knee hyperextension, which was decreased during FES and knee extensor strengthening. Weakening the knee extensors and strengthening the flexors improved SKG. During FES, weak ankle plantarflexors and strong ankle dorsiflexors resulted in increased ankle dorsiflexion, which reduced drop foot. FES also improved gait speed and reduced circumduction. These findings provide insight into compensatory strategies adopted by post-stroke patients that can guide the design of individualized rehabilitation and treatment programs.

[Treatment Options for Neurogenic Drop Foot: A Systematic Literature Research]. / Behandlungsoptionen beim neurogenen Lähmungsfuß ­ eine systematische Literaturrecherche.

Background Neurogenic drop foot may be caused by central or peripheral lesions of the nervous system. Depending on whether the first or second motor neuron is damaged, a flaccid or spastic drop foot develops. Spastic drop foot persists as a residual long-term complication after stroke in about 14 % of patients. Various conservative and surgical treatment options are available. Methods This article is based on a systematic literature review for medical evidence of functional electrical stimulation (FES) with the keywords "functional electrical stimulation AND drop foot" and "functional electrical stimulation AND gait AND stroke" in PubMed and Cochrane databases. Randomised controlled trials and cohort studies of the past 10 years were selected according to specific criteria. Additionally, four guidelines were included. Results Current guidelines provide little guidance for practical treatment and fail to give due consideration to new surgical procedures such as neural implants. In 18 randomised controlled trials on FES in stroke patients with drop foot, the FES-treated population showed either significant superiority or non-inferiority versus control. Two cohort studies confirmed significant improvements by FES. Conclusion The analysis demonstrates the importance of considering causes and severity of drop foot as well as patients' pre- and post-operative conditions for choosing treatment options. For active, high-demand patients, neural implants are valuable treatment options.

Does a foot-drop implant improve kinetic and kinematic parameters in the foot and ankle?

INTRODUCTION: Unlike the drop foot therapy with ortheses, the therapeutic effect of an implantable peroneus nerve stimulator (iPNS) is not well described. IPNS is a dynamic therapy option which is placed directly to the motoric part of the peroneal nerve and evokes a dorsiflexion of the paralysed foot. This retrospective study evaluates the kinematics and kinetics in drop foot patients who were treated with an iPNS. MATERIALS AND METHODS: 18 subjects (mean age 51.3 years) with a chronic stroke-related drop foot were treated with an implantable peroneal nerve stimulator. After a mean follow-up from 12.5 months, kinematics and kinetics as well as spatiotemporal parameters were evaluated and compared in activated and deactivated iPNS. Therefore, a gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model was performed. RESULTS: The study showed significantly improved results in ankle dorsiflexion from 6.8° to 1.8° at the initial contact and from -7.3° to 0.9° during swing phase (p ≤ 0.004 and p ≤ 0.005, respectively). Likewise, we could measure improved kinetics, i.a. with a statistically significant improvement in vertical ground reaction force at loading response from 99.76 to 106.71 N/kg (p = 0.043). Enhanced spatiotemporal results in cadence, douple support, stride length, and walking speed could also be achieved, but without statistical significance (p > 0.05). CONCLUSIONS: The results show statistically significant improvement in ankle dorsiflexion and vertical ground reaction forces. These facts indicate a more gait stability and gait efficacy. Therefore, the use of an iPNS appears an encouraging therapeutic option for patients with a stroke-related drop foot.

Hip and knee effects after implantation of a drop foot stimulator.

BACKGROUND: An active ankle dorsiflexion is essential for a proper gait pattern. If there is a failure of the foot lifting, considerable impairments occur. The therapeutic effect of an implantable peroneus nerve stimulator (iPNS) for the ankle dorsiflexion is already approved by recent studies. However, possible affection for knee and hip motion after implantation of an iPNS is not well described. OBJECTIVE: The objective of this retrospective study was to examine with a patient cohort whether the use of iPNS induces a lower-extremity flexion withdrawal response in the form of an increased knee and hip flexion during swing phase. METHODS: Eighteen subjects (12 m/6 w) treated with an iPNS (ActiGait®, Otto Bock, Duderstadt, Germany) were examined in knee and hip motion by gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model after a mean follow up from 12.5 months. The data were evaluated and compared in activated and deactivated iPNS. RESULTS: Only little changes could be documented, as a slight average improvement in peak knee flexion during stand phase from 1.0° to 2.5° and peak hip flexion in stance from 3.1° to 2.1° In contrast, peak knee flexion during swing appeared similar (25.3° to 25.7°) same as peak hip flexion during swing. In comparison with the healthy extremity, a more symmetric course of the knee flexion during stand phase could be shown. CONCLUSIONS: No statistical significant improvements or changes in hip and knee joint could be shown in this study. Only a more symmetric knee flexion during stand phase and a less hip flexion during stand phase might be hints for a positive affection of iPNS for knee and hip joint. It seems that the positive effect of iPNS is only based on the improvement in ankle dorsiflexion according to the recent literature.