A survey on foot drop and functional electrical stimulation

Abstract

The weakness of the lower leg muscles due to nerve damage or muscle weakness can result in foot drop, a change in gait that manifests as an inability to lift the toes of the foot when walking. Foot drop results in a decreased quality of life, with unassisted movement becoming difficult or impossible. The increased risk of falls is particularly problematic as foot drop often affects the elderly or infirm for whom falling already presents a great danger. Current treatment options include fixed ankle–foot orthosis (AFO) aiming to provide rigid support to the foot if the impairment is mild or surgical intervention and functional electrical stimulation (FES) devices if the weakness is more severe. FES intervention is effective for providing a non-invasive treatment in even severe cases of foot drop. Limitations of current models relate to the non-naturalistic recreation of gait in the affected leg and its unsuitability for patients with extensive peripheral nerve damage. Although there are attempts to enhance integration of sensory information and mimic natural stimulation patterns, the focus on restoring a natural feedback loop is still amiss. Without such a closed loop feedback, restoration of a natural gait pattern is unlikely to occur. We here recommend, integration of motor output from multiple muscles, information about the inputs from higher-order controllers, recorded from the intact leg with a closed loop system to improve the effectiveness of FES.