Peroneal (Fibular) Nerve Injury
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What is a peroneal nerve injury?
A peroneal nerve injury affects a major nerve in your leg called the fibular or common peroneal nerve. This nerve starts in the back part of your knee and allows you to feel the outsides of the lower legs, the tops of the feet, and the skin between the big toe and second toe. It also controls some of the muscles in the leg and the foot.
If the peroneal nerve is injured, your legs and feet may feel numb, and you may have difficulty moving them. The peroneal nerve can be damaged by leg injuries like a dislocated knee, a broken bone, or surgery complication.
You can also injure it by wearing high heels for long periods of time. Treatment depends on how severe your injury is, but can include surgery to repair or replace the damaged nerve.
What are symptoms of peroneal nerve damage?
Nerves aren’t only involved in the sense of touch. Nerves are the “highways” that electrical activity travels on. Muscles are activated and fueled by this electrical activity. If there is any damage or disturbance to the highway (nerves), muscles may not work properly since electrical signals cannot be delivered to them. —Dr. Brian Walcott
The first sign of injury may be tingling on the outer edge of the leg and thigh, the area between the big toe and second toe, and the top of your foot. Next you’ll feel numbness, which means that the injury has progressed, or is more severe.
If the injury is severe, you may have difficulty moving your foot in different directions. One hallmark symptom of a peroneal nerve injury is the inability to point your toes or your foot up toward the ceiling or point it outward.
You may also notice your foot is pointing to the floor when you stand, a condition known as “foot drop.” This can make it difficult to walk, and you may find yourself stumbling over roots, curbs, and steps.
- Numbness and tingling in the top of the foot or in the outer part of the thigh or leg.
- Numbness and tingling of the skin between the big toe and second toe.
- Tripping or being clumsy: this occurs because your foot may “hang” down toward the floor.
- Foot drop: the affected foot drags on the floor.
- Weakness in pointing your foot/toes up toward the ceiling.
- Difficulty walking.
- Muscle loss (atrophy) in the outer edge of the leg.
Other symptoms you may have
If you have a type of peroneal nerve injury called deep peroneal nerve entrapment (also known as anterior tarsal tunnel syndrome), you may have only the following symptoms:
- Tingling or vague pain of the top of the foot and skin between the big toe and second toe.
- Inability to point your second, third, and fourth toes upward (but your big toe is normal).
Causes of a peroneal nerve injury
The common peroneal nerve runs very close to the surface of your skin just below the knee, which is why it is so easy to injure. It can become injured in the following ways:
- A cut through the nerve (such as by trauma or during an orthopedic surgery).
- A broken bone or dislocated knee puts pressure on the nerve.
- Too much pressure is placed on the nerve by you crossing your legs or laying on the nerve for too long.
- A tumor or cyst is pushing on the nerve.
Injury to the peroneal nerve can occur in any activity and sport where the knee is stressed. Snow skiers and snowboarders are particularly susceptible. Falling and landing directly on the knee puts it at risk for soft tissue injury and dislocation. Since the nerve is so close to the knee joint, it can be injured as well. —Dr. Walcott
You may be more susceptible to a peroneal nerve injury if you:
- Need prolonged bed rest (after a surgery or medical procedure) where you may put weight on the fibular nerve for an extended period of time.
- Had prior bone fractures or knee dislocations.
- Wear poorly fitting shoes or wear high heels for a long period of time.
- Cross your legs for a long period of time.
- Have certain conditions, like diabetes, autoimmune diseases, or anorexia, according to the U.S. National Library of Medicine.
If you had a traumatic leg injury, like a broken bone, knee dislocation, or a deep wound through your leg, you should seek medical attention right away. Alert your doctor if you have any tingling or numbness in your leg. You may have damaged the peroneal nerve, which would need to be repaired with surgery.
If symptoms come on slowly, without a traumatic incident, call your doctor as soon as you notice them. The doctor will likely refer you to an orthopedic surgeon, neurologist (nerve specialist), or neurosurgeon, who may recommend further testing with MRI, nerve ultrasound, or a nerve conduction study.
If you do not see a doctor to diagnose the condition, the numbness and paralysis could become permanent.
Peroneal nerve injury treatment
Most people expect the diagnosis to be straightforward. While the history and physical exam can be helpful, more studies are often needed. These can include MRI, ultrasound, electromyography, and/or a nerve conduction study. —Dr. Walcott
Seeing a doctor as soon as possible can help prevent long-term damage. Treating it will also help minimize your pain and increase your mobility.
Treatment depends on the severity of the nerve damage. This may include letting the nerve heal on its own or may require surgery to repair or replace the nerve, or to remove a tumor or growth causing nerve injury. Medications can help control symptoms.
Non surgical treatments include:
- Time to let the nerve heal.
- An orthotic boot device to keep your foot up and to help you walk.
- Physical therapy.
- Ankle brace.
- Over-the-counter pain medications.
- You may have to avoid wearing high heel shoes and crossing your legs.
If you have a deep fibular nerve entrapment injury:
- Change your shoes from high heels or tight-fitting shoes to supportive shoes with a well-padded tongue.
- Try different shoe lacing configurations.
- Splint the ankle at night.
Your surgeon may recommend any of these surgeries, depending on what caused the fibular nerve injury. Depending on the surgery, they may be outpatient procedures, but many will require you to stay in the hospital for a little bit:
- Repair of the nerve (putting the nerve back together if it is apart).
- Replacement of the nerve (also called grafting).
- Fixing the fracture or dislocation that is pressing on the nerve.
- Removal of the tumor of cyst that is pressing on the nerve.
Recovery depends on the extent of the nerve damage. It is important to closely follow your doctor’s treatment plan and have frequent monitoring during the course of your treatment.
Elliot Stein is a second-year internal medicine resident at Vanderbilt University Medical Center, and he intends to sub-specialize in cardiovascular disease. He graduated magna cum laude with an undergraduate degree in molecular and cellular biology from Harvard College in 2013. He obtained his MD and Master of Science in Translational Research (MSTR) from the University of Pennsylvania Perelman School of Medicine in 2019. He stayed at the University of Pennsylvania to complete his internship year 2019-2020 at Pennsylvania Hospital. Elliot also served as an emergency medical technician (EMT) in two countries and three US states before beginning his medical career. He joined Buoy Health in 2018 because of its promise to use new technology to deliver higher quality medical information to anyone regardless of ability to access medical care.