45F training for her first marathon. Race is in September. Presents with 2 week history of numbness to the lateral left leg. Aggravated with plantarflexion and relieved with dorsiflexion.
60F with history of left knee osteoarthritis presents with sudden onset of left foot drop. Patient was wearing a tight fitting over-the-counter knee brace while walking during a European vacation to provide relief of her knee symptoms.
20 yo football/soccer player – tackle to right lateral knee. Initially pain over lateral knee which resolved within 3 days. Then he noticed decreased sensation on dorsum of left foot.
The common peroneal nerve (CPN), also known as the fibular nerve, is derived from the L4, L5, S1, and S2 nerve roots. This along with the tibial nerve are the two terminal branches of the sciatic nerve. The peroneal nerve is prone to stretch and direct injury due to its posterolateral location. The CPN separates from the tibial nerve in the superior aspect of the popliteal fossa. It crosses posterior to the lateral head of the gastrocnemius through the posterior intermuscular septum and becomes subcutaneous while it curves around the head of the fibula deep to the peroneus longus muscle.
There are three branches of the peroneal nerve:
(1) Lateral cutaneous nerve of the calf
(2) Superficial peroneal nerve (SPN)
(3) Deep peroneal nerve (DPN).
Superior Peroneal Nerve:
Motor: Peroneus Longus and Brevis muscles
Sensory: Lateral lower leg and dorsum of the foot
Deep Peroneal Nerve:
Course: runs along the anterior cortex of the fibula and then travels anterior and medial to the intermuscular septum between the anterior and lateral compartments. This is a potential point of entrapment.
Fibrous band at the origin of the peroneus longus muscle
Severe ankle inversion injuries
Direct blunt trauma
Lower extremity neuropathies
Positioning during anesthesia
Prolonged bed rest
Use of Pneumatic compression devices
Signs and symptoms will vary depending on the severity and location of the injury
most common symptom
“catching toes while walking”
can be acute or chronic
First toe web space
If concurrent traumatic injury
Due to weakened/paralyzed ankle dorsiflexors
Affected knee is lifted higher during swing phase to avoid dragging toes on the floor
Forefoot slaps to the ground after heel strike
upper lateral leg
lesion proximal to fibular head
may signal potential involvement of sciatic nerve or lumbosacral nerve root
Lower lateral leg and dorsum of the foot
Superficial peroneal nerve
First web space
Deep peroneal nerve
Foot eversion weakness (SPN)
Foot/toe dorsiflexion (DPN)
Issue with both of the above indicate lesion involving CPN
Tinel sign near fibular head
Sciatic Nerve injury
Chronic Exertional Compartment Syndrome
Amyotrophic Lateral Sclerosis (ALS)
Inflammatory demyelinating conditions
Tarsal Tunnel Syndrome
MRI and ultrasound
Determine soft-tissue sources of impingement
Can be used to help evaluate the motor and sensory axons of the peroneal nerve and its branches.
Localizes site of injury, determines severity
Can be repeated q3months to monitor recovery
EMG to Tibialis Anterior
Short head of biceps femoris and a tibial innervated muscle distal to the knee to identify more proximal lesions and/or injury to the sciatic nerve
When these studies indicate more advanced disease than surgical intervention may be indicated
>50% conduction delay and evidence on EMG of substantial disruption of the CPN innervation to the musculature than surgical nerve decompression is indicated and may increase the likelihood of a favourable outcome
Cessation of leg crossing
Padding on the prominent fibular head after direct traumatic injury. These may be worn at night to prevent compression while sleeping
PT and orthotic devices
Stretching the contralateral muscles groups
Electrical stimulation for substantial muscle weakness
Progressive strengthening of dorsiflexors and evertors once autonomous muscle contraction is present
Prognosis dependent on degree of dysfunction at presentation
Contusion, stretch injuries, lacerations, crush injuries should be assessed to determine the degree of functional loss
Neuropraxia = monitor
Complete motor or sensory loss = Surgery
Surgical exploration and decompression with rapidly deteriorating lesion with no improvement within 3 months
Surgical exploration within 72 hours, attempt at primary repair
If unable to perform primary repair due to significant gapping = nerve grafting
Nerve transfer also possible
Excision of a compressive mass
Masses that are causing significant or progressive motor loss should be removed
Approach with caution
Schwannoma, neurofibroma, intraneural ganglion cyst from superior tibiofibular joint should be dissected free, with the stalk traced and disconnected from the joint to prevent recurrence
Surgical decompression if no improvement with non-surgical approach
Minimum 3 months
Nerve function improvement may be seen for up to 6 months
If patient fails to show clinical signs of improvement or if motor loss is rapidly progressive, decompression is warranted
Evidence of severe conduction loss or disruption of motor innervation
Neurolysis = 97% return to function
Author: Dr. Alessandro Francella, MD, CCFP, Dip. Sport Med. (Jul 31, 2019 PR ND)
Poage C, Roth C, Scott B. Peroneal Nerve Palsy: Evaluation and Management. J Am Acad Orthop Surg. 2016 Jan; 24(1):1-10.
Van Zantvoort A, Setz M, Hoogeveen A, Scheltinga M. Common Peroneal Nerve Entrapment in the Differential Diagnosis of Chronic Exertional Compartment Syndrome of the Lateral Lower Leg: A Report of 5 Cases. Orthop J Sports Med. 2018 Aug; 6(8).
Rutboke S. Overview of lower extremity peripheral nerve syndromes. UpToDate.com. Last Updated: Nov 2018.