Foot drop

Overview

Foot drop, sometimes called drop foot, is a general term for difficulty lifting the front part of the foot. If you have foot drop, the front of your foot might drag on the ground when you walk.

Foot drop isn't a disease. Rather, it is a sign of an underlying neurological, muscular or anatomical problem.

Sometimes foot drop is temporary, but it can be permanent. If you have foot drop, you might need to wear a brace on your ankle and foot to support the foot and hold it in position.

Symptoms

Foot drop makes it difficult to lift the front part of the foot, so it might drag on the floor when you walk. To help the foot clear the floor, a person with foot drop may raise the thigh more than usual when walking, as though climbing stairs. This unusual kind of walking, called steppage gait, might cause the foot to slap down onto the floor with each step. In some cases, the skin on the top of the foot and toes feels numb.

Depending on the cause, foot drop can affect one or both feet.

When to see a doctor

If your toes drag on the floor when you walk, consult your doctor.

Causes

Foot drop is caused by weakness or paralysis of the muscles involved in lifting the front part of the foot. Causes of foot drop might include:

• Nerve injury. The most common cause of foot drop is compression of a nerve in the leg that controls the muscles involved in lifting the foot. This nerve is called the peroneal nerve. A serious knee injury can lead to the nerve being compressed. It can also be injured during hip or knee replacement surgery, which may cause foot drop.

  A nerve root injury — "pinched nerve" — in the spine also can cause foot drop. People who have diabetes are more susceptible to nerve disorders, which are associated with foot drop.

• Muscle or nerve disorders. Various forms of muscular dystrophy, an inherited disease that causes progressive muscle weakness, can contribute to foot drop. So can other neurologic disorders, such as polio or Charcot-Marie-Tooth disease.
• Brain and spinal cord disorders. Disorders that affect the spinal cord or brain — such as stroke, multiple sclerosis or amyotrophic lateral sclerosis (ALS) — may cause foot drop.

Risk factors

The peroneal nerve controls the muscles that lift the foot. This nerve runs near the surface of the skin on the side of the knee closest to the hand. Activities that compress this nerve can increase the risk of foot drop. Examples include:

• Leg crossing. People who habitually cross their legs can compress the peroneal nerve on their uppermost leg.
• Prolonged kneeling. Occupations that involve prolonged squatting or kneeling — such as picking strawberries or laying floor tile — can result in foot drop.
• Wearing a leg cast. Plaster casts that enclose the ankle and end just below the knee can exert pressure on the peroneal nerve.