Drop Foot
- Description
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Foot drop describes the inability to raise the front part of the foot due to weakness or paralysis of the muscles that lift the foot. As a result, individuals with foot drop scuff their toes along the ground or bend their knees to lift their foot higher than usual to avoid the scuffing, which causes what is called a “steppage” gait. Foot drop can be unilateral (affecting one foot) or bilateral (affecting both feet). Foot drop is a symptom of an underlying problem and is either temporary or permanent, depending on the cause. Causes include: neurodegenerative disorders of the brain that cause muscular problems, such as multiple sclerosis, stroke, and cerebral palsy; motor neuron disorders such as polio, some forms of spinal muscular atrophy and amyotrophic lateral sclerosis (commonly known as Lou Gehrig’s disease); injury to the nerve roots, such as in spinal stenosis; peripheral nerve disorders such as Charcot-Marie-Tooth disease or acquired peripheral neuropathy; local compression or damage to the peroneal nerve as it passes across the fibular bone below the knee; and muscle disorders, such as muscular dystrophy or myositis.
Drop foot is a condition characterized by weakness or paralysis of the muscles involved in lifting the front part of the foot (the inability to raise the foot up at the ankle). This makes walking difficult, as the toes tend to drag on the ground leading to tripping and instability. Patients adapt to this by using their hip muscles to exaggerate lifting the foot above the ground (“steppage gait”), or by swinging their leg outward so that the foot can clear the ground.
- Symptoms
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Signs and symptoms of foot drop may include:
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Difficulty lifting the front part of your foot, which is sometimes the only sign of foot drop.
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Dragging your foot on the floor as you walk.
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Slapping your foot down onto the floor with each step you take.
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Raising your thigh when you walk, as if you were climbing stairs (steppage gait).
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Pain, weakness or numbness in the foot
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Foot drop typically affects only one foot. Depending on the underlying cause, however, it’s possible for both feet to be affected.
- Causes
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There are three general categories which include neurologic, muscular and anatomic. These causes may overlap. Treatment is variable and is usually directed at the specific cause.
Foot drop is caused by weakness or paralysis of the muscles below the knee involved in lifting the front part of the foot. The underlying causes of foot drop are varied. Often, neurological, muscular and anatomical problems overlap.
- Specific foot drop causes may include:
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Muscle or nerve damage. An injury to the muscles that control the ankle and toes can cause foot drop. Nerve damage, whether due to an injury to the nerves in the lower spine or leg, or to the long-term nerve damage caused by diabetes (neuropathy), may cause foot drop. In other cases, nerve damage may occur during hip or knee replacement surgery. Pressure to the nerve on the outside of the shinbone just below the knee (peroneal or fibular nerve), as you might experience if you sit with your legs crossed for too long, can trigger temporary foot drop.
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Muscle or nerve disorders. Various forms of muscular dystrophy, an inherited disease that causes progressive muscle weakness, may contribute to foot drop. Various forms of compartment syndrome, a condition characterized by the compression of nerves and blood vessels within an enclosed space, may have the same effect.
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Central nervous system disorders. Disorders that affect the spinal cord or brain — such as amyotrophic lateral sclerosis (ALS), multiple sclerosis or stroke — may cause foot drop.
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The most common cause for foot drop syndrome is an injury to the peroneal nerve at the top of the calf behind the knee. (The peroneal nerve runs along the outside of the lower leg from just below the knee to the ankle).
- Treatments
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If possible, the underlying cause must be treated. For example, if a spinal disc herniation in the lower back is impinging on the nerve that goes to the leg and causing symptoms of foot drop and then the herniated disc should be treated. If the foot drop is the result of a peripheral nerve injury, a window for recovery of 18 months to 2 years is often advised. If it is apparent that no recovery of nerve function takes place, surgical intervention to repair or graft the nerve can be considered, although results from this type of intervention are mixed.
The latest treatments include stimulation of the peroneal nerve, which lifts the foot when you step. Many stroke and multiple sclerosis patients with foot drop have had success with it.
Drop foot is most often treated with the use of braces called Ankle Foot Orthotic (an AFO). AFO braces fit into the shoe and stabilize the ankle/foot. This stabilization provides patients with a more normal and comfortable gait.
AFO Braces work by supporting the foot in a neutral position at the ankle. AFOs prevent the foot from hanging down, which in turn prevents the front part of the foot and toes from dragging on the ground. AFOs allow the patient to walk with a more normal and comfortable gait.