Functional Electrical Stimulation (FES) of the Ankle Matt Orchard Mitch Dreska

What is foot drop? Gait abnormality in which the patient experiences difficulty in dorsiflexion of the ankle, relating to the anterior muscles of the lower leg, especially the anterior tibialis It can be caused by underlying neurological or muscular issues. The most common being neurological due to damage of the common peroneal nerve. Foot drop leads to gait deviations including toe dragging, hip hiking, vaulting, and decreased heel strike. This causes an increase in energy consumption and fall risks

What causes foot drop? Muscular- trauma Nerve damage from surgery common in hip and knee replacement/repair Neurological Peripheral nerve damage, cauda equina, spinal cord, and brain injury (stroke, TBI) Disorders including MS, ALS, Charcot-Marie-Tooth, Parkinson’s, and Diabetes

Foot drop treatment Physical Therapy Surgery Braces or Splints- AFO Electrical Stimulation- FES

Ankle Foot Orthotic (AFO) A brace made to fit the lower leg to help support the foot and ankle in proper position for gait and balance. Fights foot drop by holding the foot in a more neutral or dorsiflexed position Different versions allow for more or less movement depending upon the level of function of the patient

What is an ankle FES? Used primarily to treat foot drop Secondary to many things such as stroke and MS Uses electrical stimulation of the peroneal (fibular) nerve to activate dorsiflexors during the toe off to initial contact period (swing phase) Has several proposed benefits compared to that of a traditional ankle-foot orthosis (AFO)

Comparison of benefits AFO Reduces foot drop Improves gait mechanics Prevents loss of PROM FES Reduces foot drop Improves gait mechanics Prevents loss of PROM Prevents loss of AROM Employs active muscle contraction Slows muscle atrophy Promotes motor learning Promotes neuroplastic changes

Wired Systems Wireless Systems Implanted Systems Heel switch that detects when heel is off the ground Tilt sensor that detects the angle of the shin EMG of the unaffected side to inform on what the affected side wants to do Implantable Percutaneous intramuscular electrodes are inserted through the skin using a needle (typically only in research) Intramuscular electrodes are more durable version of percutaneous electrode Epimysial electrodes are sewn directly to the surface of the muscle Nerve cuff electrodes surround the nerve cell

Where to buy? WalkAide XFT-2001 Foot Drop System Bioness L300 Uses tilt sensor to analyze movement of the leg $4,500 XFT-2001 Foot Drop System Uses a heel sensor to determine when to stimulate the nerve $1,500 Bioness L300 $6,000 ActiGait and STIMuSTEP Implantable systems Still must use heel sensor to determine when to stimulate the nerve $20,000-25,000?

Peroneal stimulation for foot drop after stroke: A systematic review Clinically significant improvements in gait speed for FDS and control groups Over 6-30 weeks FDS and AFO are effective and roughly equal in improving gait speed for those with drop foot following stroke Clinically significant improvements in TUG, 6MWT, mEFAP, and QoL for those using a single-channel surface electrode FDS system User satisfaction was significantly higher in the FDS group than the AFO group Not enough evidence to see which patients would most benefit from which device mEFAP - modified emory functional ambulation profile QoL - quality of life

Effect of Peroneal Electrical Stimulation Versus an Ankle-Foot Orthosis on Obstacle Avoidance Ability in People With Stroke-Related Foot Drop: Within-Subject Comparison Subjects who regularly use AFO were fitted with FES and tested on obstacle avoidance ability Measured by markers on their shoes and their kinematic data in relation to the objects Success rates were higher with FES than with AFO, especially those with decreased leg muscle strength, although results were small Level of function and strength is important to consider

References Dunning K, O'dell MW, Kluding P, Mcbride K. Peroneal Stimulation for Foot Drop After Stroke: A Systematic Review. Am J Phys Med Rehabil. 2015;94(8):649-64. Farley, Jeremy. Controlling drop foot: Beyond standard AFOs. Lower Extremity Review Magazine. http://lermagazine.com/article/controlling-drop-foot-beyond-standard-afos. Published October 2009. Accessed July 17, 2016. Dapul G, Bethoux F. Functional Electrical Stimulation for Foot Drop in Multiple Sclerosis. US Neurology. 2015; 11(1): 10-8. doi: http://doi.org/10.17925/USN.2015/11.01.10. Jauch, Michael. Latest implantable and external neurostimulation technology for drop foot correction and gait rehabilitation. Advances in Clinical Neuroscience and Rehabilitation. http://www.acnr.co.uk/2013/09/latest- implantable-and-external-neurostimulation-technology-for-drop-foot-correction-and-gait-rehabilitation/. Published Sept 24, 2013. Accessed July 17, 2016. Yerworth R. Engineering Solutions to Foot Drop. University College London. https://wiki.ucl.ac.uk/display/BECS/Engineering+solutions+to+foot+drop. Published December 11, 2015. Accessed July 16, 2016. Van Swigchem R, et al. Effect of Peroneal Electrical Stimulation Versus an Ankle-Foot Orthosis on Obstacle Avoidance Ability in People With Stroke-Related Foot Drop. Journal of the American Physical Therapy Association. 2012; 92(3): 398-406. doi: 10.2522/ptj.20100405.