What is Lateral Plantar Nerve Entrapment

Lateral plantar nerve entrapment is a condition that happens when a nerve that passes from the inside of your ankle to your foot (lateral plantar nerve) gets squeezed or compressed (entrapment).

The nerve can get compressed between the muscles, bones, and connective tissue near the bottom of your heel. The nerve supplies many of your toe muscles and gives feeling to the outer toes on the bottom of your foot.

Lateral plantar nerve entrapment causes heel and foot pain that gets worse with activity.

What are the causes?

This condition is caused by compression of the lateral plantar nerve in the heel area. It can happen if the small muscles in your foot become larger from running. It may also happen because of swelling near your heel. Long-term (chronic) swelling can stiffen the connective tissue over time (fibrosis) and compress the nerve.

What increases the risk?

This condition is more likely to develop in people who:

• Are runners, especially people who run long distances or have flat feet.
• Are overweight.
• Have plantar fasciitis.
• Have extra bone growth on their heel (calcaneal spur).

What are the signs or symptoms?

Pain in the heel and foot is the most common symptom of this condition. The pain may:

• Feel sharp or achy.
• Be felt only when standing or running at first.
• Get worse until you feel pain all the time, even at rest.

How is this diagnosed?

This condition is diagnosed based on your symptoms, medical history, and physical exam. During the physical exam, your health care provider may press or tap near your arch and heel to see if that causes your symptoms. You may also have numbing medicine injected into the nerve area to see if that relieves your pain. You may have other tests, including:

• X-rays to check bone structure.
• MRI to examine your small toe muscles for decreased size (atrophy). MRI can also check nerve and tendon structures.
• Ultrasound imaging.
• An electrical study of nerve function (electromyography, or EMG).

How is this treated?

Treatment may include:

• Wearing a removable splint or boot for foot and ankle support.
• Using a soft shoe insert (orthotic).
• Using ice to reduce swelling.
• Taking pain medicine.
• Getting injections in the nerve area with medicine to reduce pain and swelling.
• Starting range-of-motion and strengthening exercises (physical therapy).
• Returning gradually to full activity. The timing will depend on the severity of your condition and your response to treatment.

If nonsurgical treatments have not helped, you may need surgery to relieve the compression. After surgery, you may need to wear a removable splint or boot for support and eventually have physical therapy.

Follow these instructions at home:

If you have a splint or boot:

• Wear the splint or boot as told by your health care provider. Remove it only as told by your health care provider.
• Loosen the splint or boot if your toes tingle, become numb, or turn cold and blue.
• If the splint or boot is not waterproof:
  • Do not let it get wet.
  • Cover it with a watertight covering when you take a bath or a shower.
• Keep the splint or boot clean.

Managing pain, stiffness, and swelling

• If directed, apply ice to the injured area:
  • Put ice in a plastic bag.
  • Place a towel between your skin and the bag.
  • Leave the ice on for 20 minutes, 2–3 times a day.
• Move your toes often to avoid stiffness and to lessen swelling.
• Raise (elevate) your foot above the level of your heart while you are sitting or lying down.

Driving

• Do not drive or operate heavy machinery while taking prescription pain medicine.
• Ask your health care provider when it is safe to drive if you have a splint or boot on your foot.

Activity

• Return to your normal activities as told by your health care provider. Ask your health care provider what activities are safe for you.
• Do exercises as told by your health care provider.

General instructions

• Do not use any tobacco products,such as cigarettes, chewing tobacco, and e-cigarettes. Tobacco can delay healing. If you need help quitting, ask your health care provider.
• Take over-the-counter and prescription medicines only as told by your health care provider.
• Keep all follow-up visits as told by your health care provider. This is important.

How is this prevented?

• Give your body time to rest between periods of activity.
• Wear comfortable and supportive shoes during athletic activity.

Contact a health care provider if:

• Your pain is not improving or is getting worse.