What is Peroneal Neuropathy?

Peroneal neuropathy is a peripheral nerve condition that occurs when the peroneal nerve, also called the fibular nerve, becomes compressed, stretched, irritated, or injured. The common peroneal nerve branches from the sciatic nerve and travels around the outside of the knee near the fibular head before dividing into the deep peroneal nerve and superficial peroneal nerve.

This nerve helps control ankle and toe movement, including lifting the front of the foot. It also helps provide feeling to parts of the outer lower leg and top of the foot. When the peroneal nerve is affected, patients may develop foot drop, tripping, ankle weakness, numbness, tingling, burning pain, or difficulty walking.

De Novo Brain & Spine evaluates adult patients with suspected or confirmed peroneal neuropathy to help determine the appropriate next step. Evaluation may include neurological examination, review of symptoms, electrodiagnostic testing such as EMG and nerve conduction studies, imaging when appropriate, conservative care recommendations, or surgical treatment planning in selected cases.

Common Signs and Symptoms

Peroneal neuropathy symptoms depend on where the nerve is affected, how severe the compression or injury is, and whether the deep peroneal nerve, superficial peroneal nerve, or common peroneal nerve is involved.

Common signs and symptoms may include:

• Foot drop, meaning difficulty lifting the front of the foot
• Tripping, dragging the toes, or catching the foot while walking
• A high-stepping gait to keep the toes from dragging
• Weakness with ankle dorsiflexion, which means lifting the foot upward
• Weakness with ankle eversion, which means turning the foot outward
• Numbness or tingling on the top of the foot
• Numbness, tingling, or burning pain along the outer lower leg
• Pain or tenderness near the outside of the knee or fibular head
• Difficulty walking on the heels
• Ankle instability or frequent stumbling
• Symptoms that worsen after leg crossing, squatting, kneeling, or pressure near the outside of the knee
• Symptoms in one leg, although both legs may be affected in selected cases

Seek prompt medical evaluation for sudden foot drop, progressive leg or ankle weakness, worsening numbness, repeated falls, symptoms after trauma, or symptoms that may also involve the back, hip, or whole leg.

What Causes This Condition?

Peroneal neuropathy occurs when the peroneal nerve is compressed, stretched, injured, or affected by an underlying medical condition. The most common site of compression is near the fibular head, where the nerve travels close to the surface on the outside of the knee.

Possible causes and risk factors may include:

• Prolonged leg crossing
• Repetitive squatting, kneeling, or pressure near the outside of the knee
• Rapid weight loss, which may reduce soft tissue protection around the nerve
• Prolonged bed rest or immobilization
• Tight casts, braces, splints, or compression around the knee or lower leg
• Knee trauma, dislocation, ligament injury, or fibular fracture
• Prior knee surgery or procedures near the nerve
• Ganglion cysts, masses, or other space-occupying lesions near the fibular head
• Diabetes or other conditions that affect nerve health
• Peripheral neuropathy or other nerve disorders
• Compartment syndrome or severe swelling in selected urgent cases
• Stretch injury involving the sciatic or peroneal nerve

These are causes or risk factors, not guarantees that peroneal neuropathy will occur. Treatment planning depends on the location of nerve involvement, symptom severity, neurological examination, electrodiagnostic findings, imaging findings, medical history, and the patient’s overall health.

How It Is Diagnosed?

Peroneal neuropathy is diagnosed through medical history, neurological examination, and sometimes electrodiagnostic testing or imaging. The evaluation also helps distinguish peroneal neuropathy from lumbar radiculopathy, especially L5 radiculopathy, as well as sciatic neuropathy, plexopathy, peripheral neuropathy, or muscle disorders.

Common diagnostic steps may include:

• Medical history and symptom review to understand foot drop, numbness, tingling, pain, falls, injury history, leg positioning, bracing, surgery, and symptom duration
• Neurological examination to evaluate strength, sensation, reflexes, coordination, gait, ankle movement, toe movement, and heel walking
• Physical examination near the fibular head to assess tenderness, nerve irritation, or symptoms reproduced by pressure near the outside of the knee
• Electromyography, also called EMG, to evaluate muscle and nerve function when needed
• Nerve conduction studies, also called NCS, to measure how well the peroneal nerve carries electrical signals across the knee, lower leg, ankle, and foot
• Ultrasound of the peroneal nerve in selected cases to evaluate nerve swelling, compression, cysts, or nerve position
• MRI of the knee, leg, or pelvis in selected cases when a mass, cyst, trauma-related injury, or structural compression is suspected
• Lumbar spine MRI in selected cases when symptoms may be coming from nerve root compression in the lower back
• X-rays or CT imaging in selected cases when fracture, bone injury, or structural abnormality is suspected
• Blood tests in selected cases when diabetes, inflammatory disease, nutritional deficiency, or other medical causes of neuropathy are being considered

The goal of diagnosis is to confirm whether the peroneal nerve is compressed or injured, identify the location and severity of nerve involvement, and determine whether non-surgical care or surgical evaluation may be appropriate.

Treatment Options

Peroneal neuropathy treatment depends on the cause, location of nerve involvement, severity of weakness, duration of symptoms, electrodiagnostic findings, imaging findings, medical conditions, gait safety, and response to prior care. Not every patient needs surgery.

Treatment options may include:

• Activity modification to reduce pressure on the outside of the knee and avoid positions that worsen symptoms
• Avoiding prolonged leg crossing, squatting, or kneeling when these positions irritate the nerve
• Padding or protective positioning around the fibular head when pressure is contributing to symptoms
• Physical therapy to improve strength, balance, gait, flexibility, and safe walking mechanics
• Ankle-foot orthosis, also called an AFO brace, to help support the foot and reduce tripping when foot drop is present
• Pain or nerve symptom medication when medically appropriate for burning, tingling, or neuropathic pain
• Treatment of contributing medical conditions, such as diabetes, inflammatory disease, or peripheral neuropathy when relevant
• Removal or treatment of a compressive lesion such as a ganglion cyst or mass when one is identified
• Peroneal nerve decompression surgery in selected cases when nerve compression is significant, symptoms are persistent or progressive, or weakness threatens function
• Nerve repair, grafting, or tendon transfer in selected traumatic or severe cases depending on the type and timing of injury
• Follow-up after treatment to monitor strength, sensation, gait, foot drop, and nerve recovery when appropriate

The purpose of surgical treatment is to reduce pressure on the peroneal nerve or address a structural cause of nerve injury when appropriate. The safest plan depends on whether the nerve is compressed, stretched, traumatically injured, or affected by another condition.