Peroneal nerve palsy is a neurological condition characterized by foot drop, caused by dysfunction of the common peroneal nerve or its branches. It can result from compression, traction, or injury to the peroneal nerve along its course, particularly at the fibular head where it is most vulnerable. The condition leads to impaired dorsiflexion and eversion of the foot, causing significant gait disturbance and functional limitation.
How Common It Is and Who Gets It? (Epidemiology)
Peroneal nerve palsy is one of the most frequent mononeuropathies of the lower limb, often seen in patients who maintain prolonged positions of knee flexion or leg crossing.
- It is frequently associated with trauma, external compression, or rapid weight loss, which reduces the protective soft tissue at the fibular head.
- Skiers, runners, and individuals wearing tight footwear are also at risk, particularly for deep peroneal nerve entrapment.
- Metabolic conditions like diabetes predispose individuals to nerve injury due to peripheral neuropathy.
Why It Happens – Causes (Etiology and Pathophysiology)
The primary causes of peroneal nerve palsy include:
- Compression: The most common cause, resulting from leg crossing, prolonged squatting, or tight casts/braces.
- Trauma: Particularly from fractures or dislocations around the knee, especially fibular neck fractures.
- Iatrogenic: Injury during orthopedic procedures, such as total knee arthroplasty or hip surgery.
- Metabolic and systemic factors: Conditions like diabetes and other neuropathic disorders increase the likelihood of peroneal nerve injury.
The common peroneal nerve winds superficially around the fibular head before splitting into superficial and deep peroneal nerves, making it susceptible to external pressure.
How the Body Part Normally Works? (Relevant Anatomy)
The common peroneal nerve arises from the L4–S2 spinal roots as part of the sciatic nerve and travels along the lateral aspect of the popliteal fossa before wrapping around the fibular head.
- It splits into:
- Superficial peroneal nerve, responsible for foot eversion (controlling peroneus longus and brevis muscles).
- Deep peroneal nerve, responsible for dorsiflexion and toe extension (controlling tibialis anterior, extensor hallucis longus, and extensor digitorum longus).
The deep peroneal nerve passes beneath the extensor retinaculum between the extensor hallucis longus and extensor digitorum longus tendons. It provides sensory input to the first webspace of the foot.
The common peroneal nerve is vulnerable to external pressure due to its superficial location around the fibular neck.
What You Might Feel – Symptoms (Clinical Presentation)
Motor symptoms:
- Foot drop: Inability to lift the front of the foot.
- Weakness of eversion: Leading to compensatory steppage gait, where the patient lifts the knee high to prevent the foot from dragging.
Sensory symptoms: - Numbness, tingling, or burning sensations along the lateral leg, dorsum of the foot, and especially the first web space in deep peroneal involvement.
Pain: - Pain may be localized at the fibular head or dorsum of the foot, exacerbated by tight shoes or dorsiflexion.
Physical findings: - Weakness in ankle dorsiflexion and eversion.
- Positive Tinel’s sign over the fibular head or dorsum of foot in deep peroneal nerve entrapment.
- Steppage gait, where the patient lifts the knee high to prevent the foot from dragging.
How Doctors Find the Problem? (Diagnosis and Imaging)
- Nerve Conduction Velocity (NCV) and Electromyography (EMG): Key diagnostic tools for assessing the site and severity of nerve injury.
- Magnetic Resonance Imaging (MRI): Useful for detecting compressive lesions such as ganglion cysts or osteochondromas near the fibular head.
- Ultrasound: Provides dynamic visualization of the nerve, especially for identifying focal compressions or cysts.
- Plain radiographs: May identify fractures or deformities contributing to nerve entrapment.
Classification
Peroneal nerve palsy is classified based on the severity of nerve damage and location of entrapment:
- Grade I: Mild neuropraxia with temporary nerve conduction block; recovery is often spontaneous.
- Grade II: Axonotmesis, where the nerve axons are damaged but the nerve sheath remains intact; recovery with intervention may take weeks to months.
- Grade III: Neurotmesis, where the nerve is severed and full recovery often requires surgical repair.
Other Problems That Can Feel Similar (Differential Diagnosis)
- Tarsal tunnel syndrome (posterior tibial nerve entrapment)
- Peroneal tendon injuries
- Lateral ankle instability (especially after an inversion sprain)
- Lumbar radiculopathy (sciatica)
- Cerebrovascular events affecting lower extremity motor function.
Treatment Options
Non-Surgical Care
Non-surgical treatment focuses on restoring nerve function and managing symptoms:
- Avoid positions and activities that cause compression (leg crossing, squatting, or tight casts).
- Anti-inflammatory medication: To reduce pain and inflammation.
- Ankle-foot orthosis (AFO): Assists foot clearance during gait and prevents falls.
- Physical therapy: Focused on strengthening dorsiflexors and evertors, along with gait training.
- Padding at the fibular head and footwear modification to reduce external pressure.
- In anterior tarsal tunnel syndrome, avoidance of tight footwear and local padding may relieve symptoms.
Surgical Care
Surgery is indicated for persistent compression or entrapment after failed conservative treatment:
- Nerve decompression: Indicated for persistent compression or entrapment at the fibular head or anterior tarsal tunnel.
- Neurolysis and excision: For compressive lesions such as ganglion cysts or osteophytes.
- Tendon transfer: Posterior tibial tendon transfer to the lateral cuneiform or dorsum of the foot may be performed in chronic foot drop to restore dorsiflexion.
- Surgical release of the extensor retinaculum: Recommended for resistant deep peroneal entrapment.
Recovery and What to Expect After Treatment
- Non-operative recovery: Mild compression injuries often recover spontaneously over weeks to months.
- Post-operative recovery: For surgical decompression, rehabilitation typically includes a gradual return to weight-bearing and gait normalization. Full recovery can take 3–6 months, depending on the severity of nerve damage and compliance with physical therapy.
Possible Risks or Side Effects (Complications)
- Persistent weakness or sensory loss despite decompression.
- Neuropathic pain or incomplete neurological recovery.
- Recurrent compression or incomplete relief after surgery.
- Gait imbalance and compensatory strain on adjacent muscles.
Long-Term Outlook (Prognosis)
- Mild compression injuries recover spontaneously with appropriate rest and activity modification.
- Severe or traumatic lesions may require surgical repair, with variable outcomes depending on the duration before intervention.
- Recurrence of entrapment after decompression is rare when causative factors are corrected. Early recognition and intervention improve long-term recovery.
Out-of-Pocket Costs
Medicare
CPT Code 64708 – Nerve Decompression: $119.08
CPT Code 64782 – Neurorrhaphy (Nerve Repair): $107.48
CPT Code 27690 – Tendon Transfer or Repair: $149.86
Medicare Part B covers 80% of the approved cost for these procedures once your annual deductible has been met, leaving you responsible for the remaining 20%. Supplemental Insurance plans such as Medigap, AARP, or Blue Cross Blue Shield typically cover that remaining 20%, minimizing or eliminating any out-of-pocket costs for Medicare-approved procedures. These plans work in coordination with Medicare to ensure comprehensive coverage and reduce your financial responsibility.
If you have Secondary Insurance, such as TRICARE, an Employer-Based Plan, or Veterans Health Administration coverage, it serves as a secondary payer after Medicare. These plans often cover the remaining balance, including coinsurance or small deductibles, which generally range from $100 to $300 depending on your specific plan and provider network.
Workers’ Compensation
If your peroneal nerve palsy is caused by a work-related injury, Workers’ Compensation will cover all medical expenses, including nerve decompression, nerve repair, and tendon transfer. You will not have any out-of-pocket expenses, as the employer’s insurance carrier directly pays for all covered treatments.
No-Fault Insurance
If your nerve palsy is related to an automobile accident, No-Fault Insurance will generally cover the entire cost of your treatment, including surgery and follow-up care. The only potential out-of-pocket expense may be a small deductible or co-payment based on your policy terms.
Example
Linda Turner developed peroneal nerve palsy following a knee injury, requiring nerve decompression (CPT 64708) and tendon transfer (CPT 27690). Her estimated Medicare out-of-pocket cost for the tendon transfer was $149.86. Since Linda had supplemental insurance through Blue Cross Blue Shield, her remaining balance was fully covered, leaving her with no out-of-pocket expenses for the procedures.
Frequently Asked Questions (FAQ)
Q. What is peroneal nerve palsy?
A. Peroneal nerve palsy is a condition caused by damage or compression of the peroneal nerve, leading to weakness or paralysis in the muscles that lift the foot and toes.
Q. What are the symptoms of peroneal nerve palsy?
A. Symptoms include foot drop, numbness or tingling on the top of the foot or outer part of the lower leg, and difficulty lifting the foot or toes.
Q. What causes peroneal nerve palsy?
A. Causes include trauma, compression of the nerve at the knee, prolonged crossing of the legs, weight loss, or medical conditions such as diabetes or nerve tumors.
Q. How is peroneal nerve palsy diagnosed?
A. Diagnosis is made through physical examination, patient history, and diagnostic tests such as nerve conduction studies, electromyography, and imaging studies.
Q. What is foot drop in the context of peroneal nerve palsy?
A. Foot drop is the inability to lift the front part of the foot, causing it to drag while walking, and is a common symptom of peroneal nerve palsy.
Q. What nonsurgical treatments are available for peroneal nerve palsy?
A. Nonsurgical treatments include physical therapy, bracing or orthotics, activity modification, and medications to manage pain or underlying conditions.
Q. When is surgery considered for peroneal nerve palsy?
A. Surgery is considered when nonsurgical treatment fails, or if there is a clear cause such as a mass compressing the nerve, or severe trauma requiring nerve repair.
Q. What types of surgery are used to treat peroneal nerve palsy?
A. Surgical options include nerve decompression, nerve repair, nerve grafting, or tendon transfer procedures.
Q. What is the prognosis for recovery from peroneal nerve palsy?
A. Prognosis depends on the cause and severity of the nerve damage; some patients recover fully, while others may have lasting weakness or require long-term use of braces.
Q. How long does it take to recover from peroneal nerve palsy?
A. Recovery time varies from weeks to months, and sometimes longer, depending on the extent of nerve injury and the effectiveness of treatment.
Q. What causes peroneal nerve palsy?
A. It can result from compression, trauma, or surgical complications, especially after fractures or procedures near the fibular head.
Q. How is peroneal nerve palsy treated?
A. Initial treatment involves rest, anti-inflammatory medications, and physical therapy. If symptoms persist, surgery may be needed.
Q. What are the symptoms of peroneal nerve palsy?
A. Symptoms include foot drop, weakness in foot eversion, numbness, and tingling along the lateral leg and foot.
Q. When is surgery required for peroneal nerve palsy?
A. Surgery is necessary if conservative measures fail, or if there’s persistent foot drop or severe compression.
Q. What is the recovery time?
A. Recovery time varies. Non-operative cases improve within weeks to months, while surgical recovery may take 3–6 months.
Summary and Takeaway
Peroneal nerve palsy is a neurological condition causing foot drop and functional impairment due to damage to the common or deep peroneal nerve. Early diagnosis and conservative treatment can lead to full recovery, while surgical decompression may be required for severe or long-standing cases. Timely intervention improves functional outcomes and reduces long-term disability.
Clinical Insight & Recent Findings
A 2025 case report from The Journal of Orthopaedic Case Reports described a 9-year-old boy who developed acute foot drop due to compression of the common peroneal nerve by a fibular head osteochondroma.
MRI confirmed the bony outgrowth pressing against the nerve. The patient underwent early surgical excision and neurolysis, which led to complete neurological recovery within five months and full function at two years.
The authors emphasized that prompt decompression within three months of symptom onset is critical to prevent permanent nerve damage and to ensure full recovery. (“Study on peroneal nerve palsy caused by fibular head osteochondroma – see PubMed.“)
Who Performs This Treatment? (Specialists and Team Involved)
Peroneal nerve palsy treatment is managed by neurologists, orthopedic surgeons, podiatric surgeons, and rehabilitation specialists. The care team works together to provide a comprehensive approach to diagnosis, surgical management, and rehabilitation.
When to See a Specialist?
Consult a specialist if you develop foot drop, weakness in the foot or toes, or numbness along the leg or foot, especially after an injury, surgery, or prolonged compression.
When to Go to the Emergency Room?
Seek immediate care if you experience sudden foot drop, severe pain, or loss of sensation in the leg, as these may indicate an acute nerve injury requiring urgent evaluation.
What Recovery Really Looks Like?
Recovery from peroneal nerve palsy depends on the severity of nerve injury. Mild compression injuries often recover with conservative measures over weeks to months, while surgical cases require 3–6 months for full rehabilitation and functional recovery.
What Happens If You Ignore It?
Ignoring peroneal nerve palsy can lead to permanent foot drop, muscle weakness, and gait abnormalities. Early intervention helps restore function and prevent long-term disability.
How to Prevent It?
Avoid prolonged pressure on the leg, especially near the fibular head. Use proper positioning during sitting or sleeping, and wear appropriately fitted footwear to prevent nerve compression.
Nutrition and Bone or Joint Health
A balanced diet with vitamin B-complex, omega-3 fatty acids, and magnesium supports nerve repair and reduces inflammation. Maintaining good hydration and controlling blood sugar levels also improve nerve health.
Activity and Lifestyle Modifications
During recovery, avoid high-impact activities. Focus on strengthening and flexibility exercises for the lower leg to promote nerve healing and prevent re-injury.
Dr. Mo Athar
