Peroneal (Fibular) Neuropathy
Burning at the fibular head with flexion or direct pressure is characteristic of peroneal (fibular) nerve compression or entrapment at the fibular head, the most common site of compressive neuropathy in the lower extremity. 1, 2
Mechanism of Injury
The peroneal nerve is anatomically vulnerable at the fibular head where it wraps around the bone just medial to the biceps femoris tendon, making it susceptible to:
- Direct pressure from hard surfaces or rigid supports against the fibular head 1, 3
- Prolonged compression during positioning (surgical, occupational, or postural) 1, 4
- Excessive flexion at the knee which stretches the nerve over the fibular head 4
- Mass lesions such as ganglion cysts compressing the nerve at this location 5
Clinical Presentation
The most common presentation is acute foot drop (complete or partial), but patients may also experience:
- Burning pain or dysesthesias at the fibular head region 2
- Numbness in the dorsum of the foot or lateral leg 2
- Symptoms provoked by knee flexion or direct pressure over the fibular head 1, 3
Common Causes
Compression remains the most common etiology, occurring at the fibular head in the majority of cases 2, 6:
- Prolonged squatting or cross-legged sitting (occupational hazard in agricultural workers) 4
- Perioperative positioning with inadequate padding at the fibular head 1
- Direct trauma to the lateral knee 2
- Ganglion cysts or other mass lesions at the fibular head 5
- Tight or inappropriate padding that paradoxically increases pressure 1, 3
Prevention Strategies
The American Society of Anesthesiologists specifically recommends avoiding prolonged pressure on the peroneal nerve at the fibular head 1:
- Use specific padding between the outside of the leg below the knee to prevent contact of the peroneal nerve with hard surfaces 1
- Ensure padding is not excessively tight or restrictive, as this can worsen compression 1, 3
- Avoid positions that maintain prolonged knee flexion beyond comfortable range 4
Diagnostic Approach
- Electrodiagnostic studies (EMG/NCS) help identify the site of lesion and determine prognosis 2, 5
- Ultrasound imaging can identify compressive masses like ganglion cysts with high sensitivity 5
- MRI achieves >90% sensitivity for structural pathology and can evaluate surrounding soft tissues 7
Management
Conservative management is first-line for most cases 2, 8:
- Activity modification to avoid prolonged squatting or pressure on the fibular head 4
- Bracing for foot drop 2
- Physical therapy focusing on strengthening and sensorimotor function 9
- Duloxetine is recommended as first-line pharmacologic treatment for painful neuropathy 9
Surgical decompression should be considered between 3-4 months for patients with persistent symptoms or incomplete recovery, even if confined to sensory dysfunction 8. Surgery is indicated earlier for:
- Compressive masses (ganglion cysts) 5
- Acute lacerations 2
- Severe conduction changes on electrodiagnostic studies 2
Outcomes after neurolysis are typically favorable, with excellent or good results in 80% of idiopathic cases and mean recovery time of 2.5 months 8.
Critical Pitfall
Avoid excessively tight padding when attempting to protect the nerve—this can paradoxically worsen compression and increase neuropathy risk 1, 3, 9.