Foot drop, also known as drop foot, is a general term for difficulty lifting the front part of the foot. Foot drop may cause one to drag the front of the foot on the ground when walking.
Foot drop is not a disease but rather an indication of an underlying neurological, muscular or anatomical issue.
In some cases, foot drop is temporary. In other cases, it is a permanent condition. The condition may require one to wear a brace on the ankle and foot to keep the foot in a normal position.
Foot drop causes difficulty to lift the front part of the foot, so it might drag on the floor when walking. To counter this, one might raise the thigh when walking (steppage gait) to help the foot lift from the floor. This may cause one to slap the foot down onto the floor with each step. Sometimes, the skin on the top of the foot and toes may feel numb.
Foot drop usually affects only one foot. However, depending on the underlying cause, it is possible for both feet to be affected.
Foot drop is mainly caused by weakness or paralysis of the muscles involved in lifting the front part of the foot. The underlying causes of foot drop may include:
- Nerve injury: the most common cause of foot drop is a compression of a nerve in the leg that controls the muscles involved in lifting the foot. The nerve can also be injured during knee or hip replacement surgery. A nerve root injury (pinched nerve) in the spine can also cause foot drop. Moreover, people with diabetes are more susceptible to nerve disorders that are also associated with foot drop.
- Muscle or nerve disorders: different forms of muscular dystrophy that cause progressive muscle weakness may contribute to foot drop. Other disorders such as polio or Charcot-Marie-Tooth disease can also cause foot drop.
- Brain and spinal cord disorders: disorders such as amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) or stroke may cause foot drop.
The peroneal nerve controls the muscles that lift the foot. Activities that compress this nerve may increase the risk of foot drop, including:
- Crossing the legs: this may compress the peroneal nerve on the uppermost leg
- Prolonged kneeling
- Wearing a leg cast: casts that enclose the ankle and end just below the knee can put pressure on the peroneal nerve