An Update on Peroneal Nerve Entrapment and Neuropathy

Key points

• Peroneal neuropathy is the most common compressive neuropathy of the lower extremity and the third most common focal neuropathy after median and ulnar neuropathies.
• The common peroneal nerve (CPN) is most often compressed at the bony prominence of the fibula, the superficial peroneal nerve (SPN) as it exits the lateral compartment of the leg, and the deep peroneal nerve (DPN) beneath the extensor retinaculum.
• Diagnosis rests on examination of strength, sensation and gait, supported by nerve conduction studies, electromyography (EMG), diagnostic nerve blocks and ultrasound.
• First-line treatment removes external compression, stabilizes unstable joints and reduces inflammation; many entrapments resolve with observation and activity modification.
• Surgical decompression is used for refractory cases, with most studies showing improvement in at least 80% of patients.

Overview

This review summarizes the epidemiology, risk factors, anatomy, presentation, diagnosis and treatment of peroneal (fibular) nerve entrapment. It should be considered in any patient with foot drop or pain or numbness of the lower extremity. Overall, the diagnosis carries a good prognosis, and most patients regain full nerve function after conservative or surgical treatment.

Causes and risk factors

Reported rates include 2% to 27% after high tibial osteotomies combined with fibular osteotomies, and common peroneal nerve injury in 16% to 40% of high-energy knee dislocations. A systematic review found an incidence of 0.4% after total knee arthroplasty; 66% of incomplete palsies recovered fully without surgery, but only 39% of complete palsies. Other causes include trauma, prolonged leg crossing or squatting, weight loss (20% of 150 patients with a mean loss of 10.9 kg developed peroneal neuropathy), diabetes, positioning in stirrups, casts or orthoses, and ganglion cysts.

Clinical presentation

CPN neuropathy causes weakness of ankle dorsiflexion, great toe extension and foot eversion with sensory loss over the dorsum of the foot; severe weakness produces foot drop and a steppage gait. SPN neuropathy typically causes eversion weakness with normal dorsiflexion and altered sensation in the lower lateral leg and dorsum of the foot, sparing the first web space; early on, symptoms may occur only during exercise. DPN entrapment (anterior tarsal tunnel syndrome) may cause paresthesias in the first web space, anterior ankle or dorsal midfoot pain and weakness of the muscles it supplies, or few symptoms at all; radiographs help because osteophytes and trauma are common causes.

Treatment

Initial treatment is nonsurgical, with bracing, observation and activity modification; options include nerve gliding exercises, padding of the fibular head, strengthening, an ankle-foot orthosis and ultrasound-guided hydrodissection. In one series of microsurgical decompression under local anesthesia, all 22 patients (33 legs) reported relief with no complications or recurrence over a mean 40-month follow-up; percutaneous peripheral nerve stimulation is an option for some SPN pain, though large outcome studies are lacking. Surgical results include motor improvement in 13 of 14 CPN patients, clinical improvement in 28 of 30 after neuroplasty, some improvement in pain-related quality of life in 69% of 54 SPN patients, and significant improvement in 12 of 13 patients after DPN release.

Frequently asked questions

What symptoms suggest peroneal nerve entrapment?

Foot drop, weakness of ankle dorsiflexion or foot eversion, and pain or numbness of the outer leg or top of the foot, depending on which branch is affected.

Is surgery always needed?

No. Many cases resolve with observation, activity modification and removal of external compression; surgery is reserved for entrapment that does not respond to conservative care.

How is the diagnosis confirmed?

Through clinical examination supported by nerve conduction studies, EMG, diagnostic nerve blocks and ultrasound, which can show anatomical causes such as scarring or lesions.

Source

Fortier LM, Markel M, Thomas BG, Sherman WF, Thomas BH, Kaye AD. An Update on Peroneal Nerve Entrapment and Neuropathy. Orthopedic Reviews. 2021;13(2). DOI: 10.52965/001c.24937. PMID: 34745471. This page is a summary prepared by Medpresso from the original publication and is not a substitute for the full text or for medical advice.