Definition

The peroneal nerve is found on the outside part of the lower knee. This nerve is responsible for transmitting impulses to and from the leg, foot, and toes. When damaged, the muscles innervated by the nerve may become weak and sensation may be lost. A condition called foot drop can occur. Foot drop is the inability to raise the foot upwards.

Causes

A peroneal nerve injury is commonly caused by an injury to the leg.

Trauma to the nerve can occur with:

• Broken leg bone
• Knee injury
• Surgery to leg or knee
• Ankle injuries

Prolonged pressure on the nerve can occur with:

• Sitting position
• Cast on lower leg, particularly if it is too tight
• Blood clots, tumors, or other masses

Risk Factors

Factors that may increase your chance of peroneal nerve injury include:

• Recent trauma to leg
• Having a cast on your leg
• Frequently sitting with legs crossed
• Long periods of bedrest
• Being very thin

Symptoms

Peroneal nerve injury may cause:

• Numbness or tingling in the lower leg
• Pain in foot or shin
• Foot weakness
• Prickling sensation
• Pins and needles sensation

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. An important part of your physical will be checking how well your nerves and muscles are working in certain parts of your leg. Your doctor may want to watch you as you walk.

Tests may include the following:

• X-rays
• MRI scan
• Electromyography (EMG) or other nerve conduction tests

Treatment

Talk with your doctor about the best plan for you. Options include the following:

Prevention

To reduce your chance of a peroneal nerve injury:

• Avoid crossing your legs
• Move around frequently
• If you work on your knees, wear protection
• If you have a cast on your leg, let your doctor know right away if you are having numbness or tingling.

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

Health Canada http://www.hc-sc.gc.ca

NINDS foot drop information page. National Institute of Neurological Disorders and Stroke website. Available at:
http://www.ninds.nih.gov/disorders/foot_drop/foot_drop.htm
Updated January 29, 2009. Accessed July 19, 2013.

Stewart JD. Foot drop: Where, why and what to do? Pract Neurol. 2008;8(3):158-169.