What Is Peroneal Nerve Injury?

  • Reema Devlia Master of Science - MSc Pharmaceutical Technology, King’s College London
  • Brittane L. Strahan Master of Science - MS, Nursing Education, American Sentinel College
  • Philip James Elliott B.Sc. (Hons), B.Ed. (Hons) (Cardiff University), PGCE (University of Strathclyde), CELTA (Cambridge University) , FSB, MMCA

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Overview 

A peroneal (pronounced peh-ruh-nee-uhl) nerve injury (PNI), sometimes known as a common peroneal nerve (CPN) injury, is characterised by damage or dysfunction of the peroneal nerve. The peroneal nerve is a major nerve that branches from the sciatic nerve in the lower leg, helping you to feel sensations in the front and side of your leg down to the dorsum (top) of your foot. The peroneal nerve also transmits the motor signals to muscles that allow you to lift your ankles and toes upwards (dorsiflexion) and evert the foot (turn it outwards at the ankle). 

The CPN splits into two branches around the knee and these control different movements: 

  • Deep peroneal nerve (DPN) – the DPN runs on the inside of the leg and ankle bone, and controls the muscles responsible for dorsiflexion (lifting up) of the foot at the ankle joint. It also relays sensation from the web of skin between the big and second toes
  • Superficial peroneal nerve (SPN) – the SPN is located on the outside of the leg where it is responsible for sensation of this part of the leg and the top (dorsum) of the foot. It also supplies the muscles that act to evert the foot (turn it outwards) at the ankle1

Injury to the peroneal nerve can cause pain, numbness, tingling, weakness, and a foot drop, where you cannot lift your foot upwards at the ankle when taking a step forward leading to the foot-dragging and potentially tripping you up. During walking, to compensate you have to lift up the leg with a foot drop at the knee, causing an abnormal gait (walking pattern).1

Anyone can develop a PNI and it is commonly seen in football players due to its association with knee dislocation. Several other health conditions mean you are more susceptible to PNI since they cause compression and injury to the peroneal nerve. They include:

PNI can significantly impact your daily activities and quality of life if left untreated. This article details the causes, symptoms, and diagnosis of this condition, alongside available treatment options. 

Causes of peroneal nerve injury

The causes of PNI are largely due to traumatic injuries to the knee, leg, or ankle as they result in a direct injury to the nerve.2 Trauma may include: 

  • Knee dislocation – this can stretch or compress the peroneal nerve. This can occur  in up to 40% of those who dislocate their knee
  • Knee, leg, or ankle fracture – fracturing the fibula bone can cause injury to the peroneal nerve
  • Surgery to the hip, knee, or ankle – this increases the risk of injuring the peroneal nerve due to its close proximity to the site of the operation
  • Peripheral nerve tumours – these can put pressure on the peroneal nerve as they grow. Surgical removal of these tumours may also damage the peroneal nerve1, 2

PNI can also be a result of compression of the peroneal nerve due to external compressive forces, such as:

  • Compression bandages
  • Tight plaster casts
  • Prolonged bed rest 
  • Habitual leg crossing1

Peroneal nerve injury symptoms

The most common symptom of PNI is the loss of ankle dorsiflexion, which is the inability to flex your ankles or toes upwards, resulting in a foot drop. A foot drop produces a distinct way of walking, characterised by lifting one knee higher than the other in order to raise your foot off the ground. It can be complete or partial in its severity and may develop slowly or over a shorter interval (days to weeks).1

Other symptoms that may accompany a foot drop include: 

  • Pain in your foot or leg – pain may vary and be described either as sharp and shooting or dull
  • Numbness in the top of the foot or leg 
  • Difficulty moving your foot 
  • Tingling or a pins and needles sensation in the leg or foot
  • Weakness in the lower leg1

Diagnosis of peroneal nerve injury

Other underlying medical conditions are known to have the same symptoms as PNI. Therefore it is vital to have any suspected PNI assessed by a professional to obtain an accurate diagnosis and thus appropriate treatment. 

Clinical and physical examination

Your doctor will first conduct a thorough clinical examination to ascertain your symptoms, medical history, whether you have had any recent trauma to your legs or feet and any health conditions that could contribute to a nerve injury. 

This is followed by a physical examination of the common peroneal nerve (CPN) to assess the location of the injury, pain, whether foot drop is present, the associated muscle strengths, reflexes, and sensation, and coordination between the leg, foot, and toes.1

Using Tinel’s sign is a reliable method of localising the area of injury. The test involves tapping along the course of the nerve, and if tingling is felt at the point of tapping, it indicates a positive Tinel’s sign and thus injury. If you have decreased sensation in the lower leg and top of the foot, injury may involve the SPN. Unusual sensation in the area between the big and second toe of the foot indicates DPN involvement.1,2

During the assessment of associated knee dislocations, your doctor will want to rule out an acute neurovascular injury as this could affect neurovascular structures (nerves and blood vessels) that pass from the thigh to the lower leg. If left untreated, they could potentially compromise the lower limb and necessitate amputation.1 

Imaging tests

Imaging tests can identify any dislocations, fractures, or tumours that may be putting pressure on the peroneal nerve. Tests include:

  • Ultrasound – used to detect early muscle atrophy, to visualise impaired nerve function, and to identify the exact level and extent of nerve lesions.3 It can also detect scarring2
  • Computed tomography (CT) scan – helps to identify fractures, further assess bone abnormalities,  and detect whether blood clots are compressing the peroneal nerve1
  • Magnetic resonance imaging (MRI) – is the preferred imaging test for diagnosing injuries in the soft tissue of the knee because it can identify fractures and discrete nerve lesions. This also includes a specialised MRI called magnetic resonance neurography (MRN) which can provide enhanced images of the nerves and neural structures4

Electrodiagnostic studies

Electrodiagnostic tests can help to evaluate nerve function and localise the injury.1 They include:

Electromyography (EMG)

EMG measures the electrical activity of muscles in response to nerve stimulation. It involves inserting small needles through the skin and into the muscle to detect neuromuscular abnormalities.

Nerve conduction velocity (NCV)

NCV measures the speed of conduction of an electrical impulse through a nerve. It involves placing two electrode patches on the skin over the nerve. One stimulates the nerve with the electrical impulse and the other records the nerve’s response. Decreased speed may indicate nerve damage.

Peroneal nerve injury treatment

PNI treatment pathways depend on the location of damage and its severity. If an underlying condition is causing the injury, treatment may address this first. 

Your doctor will typically recommend non-surgical treatments first to bring relief, such as:

  • Ankle-foot orthosis (AFO) – an AFO can be used in those with a foot drop as it maintains the alignment and stabilisation of the foot and prevents the foot from being dragged1,5
  • Shoe inserts – orthotics, braces, or foot splints that fit inside your shoes can help you to walk with a proper gait
  • Physical therapy – exercises such as stretching, strengthening, mobilisation, and balancing can improve the symptoms of a PNI1

Where there is no improvement with non-surgical treatment, surgery may be required to repair or relieve pressure on the nerve. Surgical treatments include:1

  • Nerve decompression – involves releasing tissues that create pressure on the nerve via a small incision at the location of the entrapment. Decompression can rapidly and significantly improve foot drop and ankle stability1
  • Nerve grafting – a piece of nerve tissue is removed from one location and used to fill the gap between two ends of the damaged nerve in order to restore function
  • Nerve transfer – entails connecting a functioning nerve to a non-functioning, damaged nerve which allows it to regain its ability to transmit movement and sensation information
  • Tendon transfer – involves restoring tendon function due to nerve injury by replacing a non-functioning tendon with a functioning one. It is used particularly to treat foot drop.6
  • Tumour removal – entails removal of tumours that are putting pressure on the nerve causing injury and dysfunction7

Prevention 

There are no definitive ways of preventing PNI, however, you can reduce the risk of developing severe injuries by: 

  • Avoiding sitting cross-legged
  • Avoiding activities that can injure or put pressure on your knee, legs, or feet 
  • Avoiding long periods of bed rest
  • Being physically active 
  • Managing health conditions appropriately such as diabetes
  • Seeking treatment immediately for any leg injuries 

Prognosis 

The outlook for PNI varies depending on the nature, location and severity of the injury. Often, your symptoms may improve or resolve over time with non-surgical treatments.

Studies have shown that when symptoms develop after a total knee replacement surgery, 62% of patients had a maximal neurologic recovery, with 38% of patients making a full recovery after a year.

However, developing PNI symptoms after a traumatic knee dislocation is associated with a poor prognosis for the long-term recovery of nerve function.1

Summary

Peroneal nerve injury is defined as damage to or dysfunction of the peroneal nerve which is responsible for controlling movement and sensation in the lower leg and foot. 

The majority of causes are traumatic events that involve direct injury to the nerve, or nerve compression from external forces. 

Symptoms include a foot drop, pain, numbness, tingling, and lower leg or foot weakness. A diagnosis can be made through a combination of clinical and physical examination, imaging, and electrodiagnostic studies to localise the injury and evaluate the nerve’s function. 

Typically, non-surgical treatments are first recommended, and if unsuccessful, surgery may be performed to repair the injury, relieve pressure, and restore nerve function. 

It is vital to visit your doctor if you believe you have any of the symptoms relating to PNI in order to achieve an accurate diagnosis and appropriate treatment to improve your function and well-being. 

References

  1. Lezak B, Massel DH, Varacallo M. Peroneal Nerve Injury. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 [cited 2024 Apr 26]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK549859/.
  2. Fortier LM, Markel M, Thomas BG, Sherman WF, Thomas BH, Kaye AD. An Update on Peroneal Nerve Entrapment and Neuropathy. Orthop Rev (Pavia) [Internet]. [cited 2024 Apr 29]; 13(2):24937. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8567814/.
  3. Huang S-W, Wang W-T. Early detection of peroneal neuropathy by ultrasound. Indian J Orthop [Internet]. 2014 [cited 2024 Apr 29]; 48(1):104–6. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3931140/.
  4. Marconi GF, Simão MN, Fogagnolo F, Nogueira-Barbosa MH. Magnetic resonance imaging evaluation of common peroneal nerve injury in acute and subacute posterolateral corner lesion: a retrospective study. Radiol Bras [Internet]. 2021 [cited 2024 Apr 29]; 54(5):303–10. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8475171/.
  5. Choo YJ, Chang MC. Commonly Used Types and Recent Development of Ankle-Foot Orthosis: A Narrative Review. Healthcare (Basel) [Internet]. 2021 [cited 2024 Apr 30]; 9(8):1046. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8392067/.
  6. Elisabeth Carolus A, Becker M, Cuny J, Smektala R, Schmieder K, Brenke C. The Interdisciplinary Management of Foot Drop. Dtsch Arztebl Int [Internet]. 2019 [cited 2024 Apr 30]; 116(20):347–54. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637663/.
  7. North RY, Snyder R, Slopis JM, McCutcheon IE. Surgical treatment of common peroneal neuropathy in schwannomatosis: illustrative cases. J Neurosurg Case Lessons [Internet]. 2021 [cited 2024 Apr 30]; 1(26):CASE21176. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9245758/.

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Reema Devlia

Master of Science - MSc Pharmaceutical Technology, King’s College London

Reema is a MSc Pharmaceutical Technology and BSc Chemistry graduate with an in-depth knowledge of solid and liquid dosage form design and regulatory affairs, alongside a proven strong background in scientific writing, literature searches and reviews. She also has experience in pharmaceutical sales, where she provided technical information relating to pharmaceutical ingredients and fulfilled regulatory requests to support customer end use and strengthen client relations.

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Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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