It's difficult to determine the exact incidence of drop foot, in part because it can be a symptom of many potential conditions—physical, neurological, or traumatic. But it's safe to assume it has been a problem since humans first started walking around.

James W Pritchett, MD, FACS, clinical associate professor of orthopedic surgery and sports medicine at the University of Washington School of Medicine in Seattle, suggests the earliest recorded case of drop foot can be found in the first book of the Bible when Jacob limps away from a wrestling match against an anonymous man. Although most debates focus on the identity of the man who inflicted Jacob's injury, there has been some question about the injury itself and its actual cause. Was the thigh dislocated? Was the injury to a local nerve and not the thigh? Was it a ruptured disk? The sciatic nerve? Some other cause?

Had Jacob experienced his struggle today, there would be no lingering doubt (spiritual nature aside). His physician would pinpoint the diagnosis using a variety of tools, from a patient medical history to medical imaging techniques. Once diagnosed, Jacob would very likely be referred to a PT for treatment of the drop foot as well as other related symptoms, if any.

The PT would conduct her own evaluation, confirming the physician diagnosis, and develop a treatment plan based on that diagnosis and the patient's individual history and health. Treatment length and result vary according to the diagnosis and methods. Some patients will never be able to fully dorsiflex their foot again; others may be able to recover a completely normal gait.

Treatment could include balance training, gait training, stretching and strengthening exercises, foot and ankle orthoses (AFOs), and/or electrical stimulation. Typically, it is some combination of these methods designed to complement each other.

According to Miriam Marie Guanche, MSPT, partner and clinical director of Miami Physical Therapy Associates (MPTA), AFOs have been the standard treatment for drop foot for some time, enjoying support from many prior cases and reimbursement from payors. But newer technologies are showing great results, including the ability to induce recovery along with function, and payors are starting to take note.

Guanche routinely uses electrical stimulation to treat drop foot, employing the FDA-approved ODFS Dropped Foot Stimulator from NDI Medical in Cleveland. As a specialist in both spinal cord and neurological injuries, Guanche treats many patients with drop foot. She notes that newer tools for electrical stimulation are becoming more common though they are not yet commonplace.

"Companies [who sell newer technologies] are developing literature to show the effectiveness of their equipment and are working with insurance firms toward reimbursement. So, while electrical stimulation is not common yet, its use is increasing," Guanche says.

DEFINING AND DIAGNOSING DROP FOOT

Electrical stimulation won't work for everyone, however. Patients with lower motor neuron injuries, peripheral nerve injuries, or fixed ankle contractures will not benefit. Subsequently, it is important to know the patient's diagnosis when creating the treatment plan.

Drop foot (or foot drop) is typically diagnosed as soon as the patient realizes the problem exists. Patients with drop foot are unable to dorsiflex or lift their toes up from the ankle. Subsequently, their foot and toes drag as they walk. "The first time patients realize they are dragging their toes, they know they have a problem," Guanche says.

Patients will compensate with exaggerated hip and knee motions, often slapping the foot against the ground. "Patients will really elevate their leg to clear the foot and will come down toes first or with a flat contact," Guanche says.

Drop foot is often a symptom of another condition and is rarely the sole problem. Guanche's patients most commonly suffer drop foot as a result of a stroke; hemiplegia; brain injury; incomplete spinal cord injury; a herniated disk causing nerve irritation or compression at the spinal level; nerve compression or entrapment located distally around the fibular head in the peripheral nerve; and/or trauma, such as a blunt injury to or sustained compression of the nerve. Guanche recalls one patient who exhibited drop foot as a result of distal nerve damage inflicted after being pinned under a car for a sustained period of time. Other causes include damage to the peroneal nerve, dorsiflexor injuries, neuropathies, drug toxicities, and diabetes.

The exact diagnosis is rendered by the physician, who determines the root cause by considering symptoms, the patient's medical history, physical and neurological exams, imaging studies (such as MRI), and electromyograms (EMGs), which record the electrical activity of muscles. "Usually, patients will have been diagnosed by a physician who has sent them to therapy with orders. We conduct our evaluation to confirm the doctor's findings and develop a plan of care," Guanche says.

TAILORING TREATMENT

Often, the PT will devise a treatment plan that works within the patient's insurance limitations, particularly in regard to length of treatment and equipment. Guanche physicians routinely order therapy three times per week for 4 weeks. "Sometimes, the treatments are to teach the patient proper exercises. Other times, there are fewer visits, intended only to help a patient acquire a proper AFO or home electrical stimulation unit and learn how to use it. And still other times, for instance stroke visits, therapy encompasses more conditions than drop foot and may take 3 to 6 months. Spinal injuries can take years.

Treatment is therefore tailored to the patient's diagnosis. "We want to perform the exercises and administer treatments that will strengthen the muscle and try to bring nerve function back," Guanche says.

Some exercise programs will focus on strengthening the ankle; in spinal cases, spinal stabilization and back exercises can be used to take pressure off the disk or the nerve causing the drop foot. Balance and gait training counteract the bad habits of drop foot walkers (including exaggerated hip flexion), and stretching prevents the Achilles tendon from becoming tight. "We want to preserve the full range of motion," Guanche says.

Guanche routinely complements exercise with electrical stimulation of the tibialis anterior to contract and re-educate the muscle and nerves; patients who exhibit a good contraction will undergo treatment with the ODFS device. However, not everyone will experience a good contraction with electrical stimulation (or be able to pay for a home device). Those for whom the method is contraindicated can often work with an AFO; the orthosis is particularly beneficial for patients whose nerves are too damaged or whose muscles are too atrophied to respond to electrical stimulation.

BRACING THE ANKLE

"The most important aspect of an AFO is a good fit. If it is too large, short, or tight, then it won't work as it should," Guanche says. In addition to fit, the AFO should also be tailored to a patient's specific condition. Guanche recommends rigid AFOs for patients who need more ankle stability; full-contact AFOs for those with severe weakness or paralysis; AFOs with a buildup to counteract increased spasticity and foot tone; lightweight, flexible, and/or articulating AFOs for patients with a localized problem, such as a herniated disk or injury to a single muscle; and articulating AFOs, which permit the dorsiflexion but prevent foot drop.

Guanche believes that custom, articulating AFOs are the best option when possible, though some patients will need the additional support available with more rigid models. "The therapist and orthotist work together to find the best AFO for each patient," Guanche says.

Even then, there is no guarantee the patient will use it. Guanche notes compliance is one of the biggest problems. "Most patients don't really like using the AFO at first. It adds weight and may require a bigger shoe. But once patients start wearing the AFO, they see how much more stability they have and how much better they walk, and they increase its use," Guanche says.

STIMULATING THE MUSCLE

Despite their positive impact on gait, however, AFOs do not produce permanent improvement, whereas early research indicates that electrical stimulation might. "If a person has the potential to recover that muscle function, electrical stimulation can force the patient to exercise and therefore build up that muscle," Guanche says.

Patients who typically benefit include those unable to dorsiflex the ankle and lift the foot due to a central nervous system injury such as stroke, spinal cord injury, multiple sclerosis, or brain trauma. According to NDI, ideal candidates for the ODFS Dropped Foot Stimulator include patients suffering dropped foot due to an upper motor neuron lesion but with lower motor neurons intact and those who have a passive ankle joint range to at least neutral; intact skin in the area of stimulation; the capability to stand and ambulate with minimal assistance or less with or without an assistive device; the motivation and ability to understand the use of the device and/or adequate caregiver support where appropriate; the ability to tolerate the sensation of stimulation; and a lack of significant medical complications.

Electrical stimulation, ODFS or otherwise, is based on the principles of regular nerve function. The brain sends neurological stimuli through the nervous system and spinal cord and to the muscle, which contracts and causes the desired movement. "Sometimes, with injury, the message does not get to the muscle," Guanche says. Electrical stimulation devices activate the muscle directly, bypassing the brain but mimicking its process and, in some instances, helping to re-establish that connection.

The ODFS instrument used by Guanche employs two electrodes that are placed on the patient's lower leg and are connected to the machine that controls the system. The control box is a small, single-channel stimulator that can be worn discreetly on the belt.

One electrode is placed at the "little bone of the fibula head," and the other is located two fingers down at the motor point of the tibialis anterior. Placement is precise and can be modified slightly to better suit a patient. If the electrodes are placed in the wrong spot, the patient will not achieve the desired dorsiflexion and will know to move them.

A cable runs from the machine to the electrodes on the lower leg and another to a switch placed inside the shoe. Neither the cable nor the switch is large enough to require a larger shoe size.

The switch is activated when the patient lifts the leg or steps down on the foot and sends corresponding signals to the control box. When the patient is standing on the switch, the control box is off. When the patient lifts his or her foot, the machine sends electrical stimulation to the electrodes, which activate the peroneal nerve and cause the muscle to contract and lift the foot. "The machine turns on and off as the foot goes up and down," Guanche says.

The ODFS is unique in that clinicians can modify the parameters to match the patient's gait and stimulation needs. One dial controls the timing of the electrical stimulation to more closely match a person's natural gait with slower and faster speeds. Another controls the intensity of the electrical stimulation. "Initially, a patient may need more intensity to generate a good contraction and bring the foot up, but as the muscle becomes stronger and more efficient, it might not need as much stimulation to get the same result," Guanche says.

According to Guanche, the ability to modify these parameters is a major benefit to the ODFS. "If you can't adjust the parameters, then a particular machine may not work for a certain patient," Guanche says. If the dorsiflexion is produced at the wrong time, the foot may still drag. Older machines may not be able to produce the intensity required to cause contraction and movement. "The ODFS is a strong little machine," Guanche says, adding that she has never had a patient with the potential to contract the muscle be unable to do so using the machine.

GETTING THE NERVE

Patients are therefore often able to resume a normal walking gait and may also receive secondary, more positive benefits, particularly if the device is used as an adjunct to physical exercise. "The ODFS treats the drop foot symptom but also stimulates the nerve and strengthens the muscle, so there is the potential for recovery," Guanche says.

A stroke victim, for example, may not know how to activate the muscle because of the brain injury, but the foot is not paralyzed—he or she just does not know how to move the foot. "The machine does muscle re-education and is a training tool," Guanche says. Guanche has seen patients grow stronger, improve their walking pattern, and even recover to the point of no longer needing the machine.

Ideally, the level of recovery would be measured using EMG studies, but this step is not routine. The test is typically performed during the diagnostic phase to determine the presence and scope of an injury, but it is rarely completed at the end of treatment, particularly if a patient has improved. "EMG studies would likely show a change in the patient's nerve conduction, but usually when patients get better, they don't have more tests done," Guanche says.

In the past, the treatment was administered during physical therapy sessions only, but today, the devices can be purchased with a prescription and brought home for longer periods of use as the patient becomes stronger. Patients must be trained, but the system is easy to use; full clinician training is often completed within 4 hours. Guanche will try the unit on the patient for two or three sessions to determine whether he or she is a good candidate. If so, MPTA will order the unit for the patient and then train him or her during the next two or three sessions. "We want to make sure they know how to properly use it and that all the settings are set to their specific parameters," Guanche says.

FOOTING THE BILL

The cost of an ODFS unit may be prohibitive for some patients, though at an approximate $1,250, it is not the most expensive system available. Some units can cost as much as three times more, and a new wireless device has broken both convenience and price barriers. MPTA received a unit to demonstrate on the patients so the practice did not actually have to put out significant capital to obtain the device. Even so, Guanche would believe it is worth it. "We cannot recommend those units that are unable to modify parameters," she says.

Research shows that the ODFS does improve patient walking speed and psychological indices for walking, but it does not yet show conclusive results regarding its comparison to AFOs. More studies are under way. One example is the research sponsored by the National Institute of Child Health and Human Development, which will examine the ability of electrical stimulation (using the ODFS) to improve the strength and coordination of the lower limb muscles in stroke survivors as compared to AFOs; results are expected in 2009. Until enough literature is compiled to convince insurers to pay, patients will have to continue to pay out-of-pocket. The cost, however, may be worth it to re-establish a normal gait and have both feet be the best foot.

Renee DiIulio is a contributing writer for Physical Therapy Products. For more information, contact .