What Is Foot Drop, and What Causes It?

Major causes of foot drop include:

• Diabetic neuropathy (a complication of diabetes)
• Stroke
• Polio
• Muscular dystrophy (an inherited condition that causes progressive muscle weakness)
• Charcot-Marie-Tooth disease (a type of inherited condition that causes damage to peripheral nerves called peripheral neuropathy)
• Multiple sclerosis
• Amyotrophic lateral sclerosis (a type of progressive disease that causes damage to the nerves and muscles)
• Nerve damage due to surgery (such as knee replacement)
• Herniated intervertebral disk in the lower back

Lifestyle or occupational factors can increase the risk of peroneal nerve injury and consequent foot drop. These include sitting with crossed legs or working in jobs that involve kneeling for long hours.

The defining symptom of foot drop is the inability to lift the front of the foot when taking a step. Because the foot drags, you may need to lift your leg higher to clear the floor. The affected foot then hits the ground, creating a characteristic slapping sound. This manner of walking is called steppage gait.

Depending on the underlying cause of foot drop, additional symptoms may be present, such as numbness and tingling sensations on the front of the leg and the top of the foot. 

Signs of damage to other nerves may be seen with conditions such as diabetes, multiple sclerosis, and amyotrophic lateral sclerosis. A disk prolapse or herniation may cause severe back pain, typically in the lower back.

The typical dropping of the foot or steppage gait helps doctors diagnose foot drop. They may take a detailed history of your injuries, health conditions, and history of surgery. They may ask you about any drugs or medications you take, including your alcohol intake.

Your doctor will then perform a detailed physical examination to assess muscle strength and mass, particularly in your legs and feet. To determine the underlying cause of the condition, they may order tests such as:

• Nerve conduction test
• Electromyography
• Nerve ultrasounds
• X-ray
• CT scan
• MRI
• Blood test

Treatment of a foot drop depends on the underlying cause. 

Certain conditions, such as multiple sclerosis and amyotrophic lateral sclerosis, are progressive and may cause permanent foot drop. In most cases, however, foot drop goes away completely with treatment. Incomplete recovery may be seen in severe cases, such as stroke.

The treatment approach generally includes the following:

• Wearing assistive devices or orthotics, such as braces, splints, or shoe inserts
• Physical therapy to strengthen the muscles
• Electrical nerve stimulation 
• Surgery if conservative treatment is not effective or the cause needs to be surgically corrected (such as a prolapsed disc). Surgery may involve fusing the bones in the ankle or foot or surgically placing a functional tendon and muscle into a part of the foot.