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Definition

A peroneal nerve injury is damage to the nerve on the outer part of the lower knee. This nerve sends impulses to and from the leg, foot, and toes. Damage can cause weakness, numbness, and pain. It may also make it hard for a person to lift their foot.

Causes

The nerve may get injured due to:

  • A broken leg
  • A knee injury
  • Surgery to the leg or knee
  • Ankle injuries
Peroneal Nerve Damage After Ankle Injury and Repair
Peroneal injury
Copyright © Nucleus Medical Media, Inc.

Too much pressure on the nerve can also cause this problem. This can happen due to:

  • Sitting position
  • A leg cast that is too tight
  • Blood clots, tumors, or other masses

Risk Factors

Things that may raise the risk of this problem are:

  • Recent trauma to the leg
  • Having a cast on a leg
  • Too much sitting with crossed legs
  • Being on bedrest
  • Being very thin

Symptoms

Problems may be:

  • Numbness or a feeling of pins and needles in the lower leg
  • Pain in the foot or shin
  • A weak foot
  • A feeling of pins and needles

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done. It will focus on the leg.

Pictures of the leg may be taken. This can be done with:

The nerves and muscles may be tested. This can be done with electromyography (EMG) or other nerve conduction tests.

Treatment

Treatment depends on what has caused the injury. Options are:

  • Therapy to strengthen leg and foot muscles
  • A supportive device, such as an ankle or foot brace to ease symptoms

People who are not helped by other methods may need surgery. It may take pressure off the nerve.

Prevention

To lower the risk of a peroneal nerve injury:

  • Avoid crossing your legs.
  • Do not put pressure on the back or side of the knee.
  • Get treated for leg injuries right away.
  • Get treated for any numbness or tingling from wearing a cast.

RESOURCES

National Institute of Neurological Disorders and Stroke  http://www.ninds.nih.gov 

Ortho Info—American Academy of Orthopaedic Surgeons  http://orthoinfo.org 

CANADIAN RESOURCES

The Canadian Orthopaedic Association  http://www.coa-aco.org 

Health Canada  https://www.canada.ca 

References

Foot drop information page. National Institute of Neurological Disorders and Stroke website. Available at: https://www.ninds.nih.gov/Disorders/All-Disorders/Foot-Drop-Information-Page. Accessed October 6, 2020.

Mononeuropathies. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/neurologic-disorders/peripheral-nervous-system-and-motor-unit-disorders/mononeuropathies. Accessed October 6, 2020.

Revision Information

  • Reviewer: EBSCO Medical Review Board Rimas Lukas, MD
  • Review Date: 09/2020
  • Update Date: 10/06/2020