By Jennifer S. McWain, MHS, PT, and Kirk Randall, PT, MS
Nearly 50 years ago, “Grandpa Ray,” who had diabetic peripheral neuropathy, had three options for controlling his foot drop: a high-steppage gaitpattern, double metal upright ankle-foot orthotics (AFOs) attached to what he affectionately referred to as his “Herman Munster shoes,” or what he ultimately resorted to—cowboy boots. Today, there is a great variety of options to address the foot drop symptom that occurs with many different disorders and diseases. The difficulty now is being knowledgeable about the plethora of products available to find the best options for each patient.
Identifying the extent and cause of foot drop is the first step in determining the best treatment options. Symptoms can vary in severity, from a patient having a heel strike but then abruptly plantarflexing (PF) into a foot slap pattern to dragging of the toes during swing phase. Foot drop sufferers may also present with high steppage or hip circumduction compensatory gait patterns. Upper motor neuron (UMN) injury etiologies include stroke, brain injury, spinal cord injury, or multiple sclerosis. Lower motor neuron (LMN) injury causes include trauma, surgery, drug toxicity, or metabolic disease. Muscular-level etiologies of foot drop include muscular dystrophy, Charcot-Marie-Tooth disease, and post-polio syndrome.
Musculoskeletal deficits may be addressed by physical therapy treatment, and home program instruction to improve flexibility and strength into dorsiflexing (DF). Strength and range of motion training tools common to most physical therapy clinics include cuff weights such as those provided by Bolingbrook, Ill-based Advantage Medical, TheraBand resistance bands, available through The Hygenic Corporation/Performance Health, Akron, Ohio, and the BAPS board, marketed by AliMed, Dedham, Mass.
For more significant PF contractures, serial casting and static and dynamic day and nighttime splints can provide a low load prolonged stretch. Many types of these devices are manufactured. For example, on the AliMed Inc website there are 24 products in this category. The products differ in sizing, adaptability, materials used, weight-bearing capabilities (including ability to off-load areas of the foot where there may be wounds or wound susceptibility), and ability to control other rotational moments. Dynasplint Systems, Severna Park, Md, and Össur, Reykjavik, Iceland, also manufacture these types of orthoses. It can be overwhelming to sort out the products in this category, so reliance on a trusted certified orthotist to help match patient needs with products can be invaluable.
Neuromuscular electrical stimulation (NMES) devices such as the Empi Continuum by Empi, a DJO Global company, Vista, Calif, or the Zynex Nexwave from Zynex Medical, Lone Tree, Colo, can be used in cases where a muscle can be stimulated to contract. Clinicians can use these handheld units in the clinic, as well as set them up for patient home use. These AC current devices, of course, will not work in a LMN injury unless substantial neural recovery has occurred. NMES can help retard atrophy and assist patients in relearning to contract the anterior tibialis muscle.
Retraining patients to contract the anterior tibialis can be enhanced with the use of surface EMG biofeedback (BFB) units that provide audio and visual feedback correlating with the degree of volitional activation. The NeuroEDUCATOR 4 system available through Therapeutic Alliance Inc, in Fairborn, Ohio, has four channels available to monitor unilateral, bilateral, agonist, and/or antagonist muscles for obtaining maximal volitional signal in a coordinated manner. The addition of monitoring motor activation while choosing home program exercises provides assurance to both patient and physical therapist that the chosen activities are indeed producing effective motor activation even when there is lack of visual motion. There are also combination NMES and BFB systems such as the MyoTrac from Thought Technology Ltd, Montreal West, Quebec, Canada, with which patients can initiate NMES to heighten contraction of the muscle after they reach a target volitional contraction guided by the BFB visual and audio display.
Whether or not recovery of motor function is in the picture, patients will typically benefit from some type of AFO intervention in the interim of recovery or as a permanent solution when recovery is not likely. The first goal of the brace is to hold up the toe so the patient does not trip during swing phase of the gait cycle. Secondly, using devices that have some flex via the property of the materials used or adding a hinge to the brace can help achieve rollover for a more fluid gait cycle and reduce energy expenditure. Alternatively, providing rigidity at the ankle can help to correct problems up the chain, such as a DF stop to reduce knee buckling or a PF stop to help reduce knee hyperextension. Adding in other kinetic chain corrections such as medial or lateral posts, can reduce stresses at the knee, hip, and spine.
Custom-made AFOs include the polypropylene type that fits in the shoe or those composed of metal uprights with leather cuff attachments that are external to the shoe. Custom braces can minimize skin contact and are more durable against stresses due to high levels of activity, high levels of spasticity, or higher body weight loads. They also can be made rigidly initially with options to articulate as patients improve in their motor control.
The availability of prefabricated AFOs is almost mind-boggling relative to the number of products and options. Manufacturers have employed biomedical engineers and orthotists to work together to produce the iconic “better mouse trap.” Among the providers of AFOs is Allard USA, Rockaway, NJ, which manufactures AFOs for adult and pediatric populations. Some of the AFO solutions Allard offers includes the ToeOFF family, which features the Ypsilon, Blue Rocker, and ToeOFF, as well as the KiddieGAIT/KiddieROCKER. Likewise, Cascade Dafo, Ferndale, Wash, provides a line of dynamic foot ankle orthoses directed at the pediatric population.
Previously, prefabricated devices were best when there was only weakness in the dorsiflexors, without significant weakness in other muscle groups, and adequate sensation was present. But recent design advances have led to the introduction of devices with inversion/eversion control, fit adjustability, and higher levels of DF assist.
Neuroprostheses are devices that use functional electrical stimulation (FES) to cause the DF to contract from toe-off through the initial contact phases of gait. Appropriate patient selection for these devices includes intact LMN, no PF contracture, minimal PF spasticity, and tolerance to electrical stimulation. Valencia, Calif-headquartered Bioness is a provider of FES neuroprostheses. The company offers its L300 Foot Drop System as a wireless, programmable device designed to enable patients affected by certain neurological conditions to walk more naturally as well as with improved balance and speed.
For patients with UMN origin of foot drop, PF spasticity management may be critical for a successful outcome. Helping patients get to physicians who specialize in the use of medical products that are known to control spasticity, including oral medications, the Medtronic intrathecal baclofen pump available through Medtronic Inc, Minneapolis, and Botox injections, marketed by Allergan Inc, Irvine, Calif, can be an important weapon in the battle against foot drop.
The following companies also market products built to address foot drop:
Anatomical Concepts Inc
Cascade DAFO Inc
DM Systems Inc
Empi, a DJO Global Company
ProCare, a DJO Global Company
Restorative Care of America Inc
Robotic-driven orthotic systems such as the Lokomat from Hocoma, with headquarters in Zurich, Switzerland, and Norwell, Mass, are becoming more commonplace in rehabilitation facilities and are showing high value at incorporating returning levels of DF motor control into the gait pattern. Ankle-rehabilitation robots are in development at many biomedical engineering facilities.
Though not yet commercially available, these devices are intended to allow for: 1) multiple types of exercises, 2) feedback to aid in determining diagnosis, prognosis, and customization of therapy, and 3) therapy to be delivered at greater frequency, duration, and intensity than is currently available due to limited resources.
Ideally, these types of devices will not only be important pieces of equipment in rehabilitation clinics across the world but will also become a mainstay in providing tele-rehabilitation for patients without access to rehabilitation facilities. Two examples of devices in development are the Rutgers Ankle, from Rutgers University, New Brunswick, NJ, a device that works off of a platform; and the MIT Anklebot, available through Massachusetts Institute of Technology, Cambridge, Mass, a device worn by the patient.
Progress and Prevention
Perhaps one of the greatest advances in all of the therapies now available for people with foot drop is the protection of the limb. “Grandpa Ray,” who opted against the AFOs and instead chose cowboy boots, soon developed ulcerations on both feet, which ultimately resulted in the need for bilateral above-the-knee amputations. Since then, the progress of products, both in function and limb protection, would have helped Grandpa Ray make a different decision. PTP
Jennifer S. McWain, MHS, PT, graduated from Grand Valley State University with a bachelor of science degree in physical therapy in 1989, and from the University of Indianapolis with a MHS degree with focus on neurological physical therapy in 1993. She has worked at Mary Free Bed Rehabilitation Hospital in Grand Rapids, Mich, for 24 years in inpatient therapy, outpatient therapy, pediatric and adult spasticity management clinics, and the adult amputee clinic. McWain has been a primary physical therapist with multiple specialty programs, including stroke, amputee, spinal cord injury, and cancer rehabilitation.
Kirk Randall, PT, MS, graduated from Grand Valley State University in 1993. He has worked at Mary Free Bed Rehabilitation Hospital in Grand Rapids, Mich, for 27 years. He is the primary physical therapist with the outpatient stroke, brain injury, and cancer rehabilitation programs, and has expertise in both inpatient and outpatient orthopedics and neurological rehabilitation. For more information, contact PTPEditor@allied360.com.
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