Symptoms and causes
Peroneal neuropathy: foot drop, leg crossing and recovery
One nerve runs around the outside of the knee, directly over bone, under thin skin. It is the most commonly compressed nerve in the leg, and the things that squeeze it are often ordinary: crossed legs, a cast, a long operation, or losing weight.
Written by the Managing Neuropathy editorial team under the direction of Dr. Tom Biernacki, DPM, FACFAS · Clinical review pending · Last updated 24 September 2026
The short answer. The common peroneal nerve, also called the common fibular nerve, wraps around the outside of the knee at the top of the fibula. Pressure there causes weakness lifting the foot, numbness across the top of the foot and the outer shin, or both. Most cases from pressure improve once the pressure stops, and a brace keeps you walking safely meanwhile. If it is not improving after about three months, or is getting worse, surgery to release the nerve is considered.
Where the nerve runs, and why that matters
The sciatic nerve divides above the back of the knee. One half, the common peroneal nerve, travels around the outside of the knee at the neck of the fibula, the slim outer bone of the lower leg. At that point it sits against bone with very little padding, which is why it is the most frequently compressed nerve in the lower limb, and second only to the median and ulnar nerves in the arm among nerves that get trapped anywhere.
Just past the knee it splits into two branches, and which one is affected shapes what you notice:
| Branch | What it does | What its loss looks like |
|---|---|---|
| Deep peroneal | Lifts the foot and toes; sensation in the web between the first and second toes | Foot drop, toe drag, a small numb patch between the big and second toes |
| Superficial peroneal | Turns the foot outward; sensation over most of the top of the foot and the outer lower leg | A foot that turns in or rolls; numbness across the top of the foot |
| Both, at the fibular neck | All of the above | Foot drop with numbness on the top of the foot and the outer shin |
What pinches it
- Habitual leg crossing, especially in people who have lost weight or are thin, and especially when a leg is crossed for long periods at a desk or in a car.
- Weight loss. The fat pad over the fibular neck is part of the nerve’s protection. Rapid loss, from illness, surgery or intentional weight loss, removes it.
- Squatting and kneeling for long stretches: gardening, laying flooring, farm work.
- Casts, splints, tight wraps and braces that press on the outside of the knee.
- Prolonged bed rest or a long operation, where the leg lies rolled outward against the mattress or table for hours.
- Knee injury or surgery, including knee replacement, arthroscopy and knee dislocation, which carries the worst outlook of the group.
- A ganglion cyst arising from the knee joint and tracking into the nerve. Uncommon, and a reason why imaging is sometimes ordered.
Two other conditions increase the nerve’s vulnerability to all of the above: diabetes, and the inherited neuropathies, which make nerves more susceptible to pressure.
What it feels like
The commonest presentation is weakness lifting the front of the foot, which produces the catching, slapping gait of foot drop. People usually notice the toe catching on a step, a scuffed shoe on one side, or the foot slapping down.
The sensory version is quieter and often missed: numbness or tingling across the top of the foot and the outer part of the lower leg, with normal strength. It is one of the few causes of numbness on the top of one foot, and it is frequently mistaken for the start of a general neuropathy. Both feet going numb together is a different problem. Numbness by location.
Pain is not the main feature. A deep ache at the outside of the knee can be there, but burning pain in both feet points elsewhere.
How it is diagnosed
Strength lifting the foot and turning it outward, compared with turning it inward, which is supplied by a different nerve. That comparison is what separates a peroneal problem from an L5 nerve root problem in the back.
Tapping along the nerve where it crosses the bone can send tingling into the foot, a positive Tinel sign, which points to the level of the trouble.
These localize the problem and grade it: whether the signal slows only across the knee, and whether the muscle has lost nerve supply. What the tests involve.
Ultrasound or MRI looks for a ganglion cyst or another lesion, and X-rays for bony causes. Not everyone needs imaging.
Treatment
The first treatment is removing the cause, and it is more effective than anything that follows. Stop crossing your legs. Change how you kneel, or use a raised seat. Get the cast or brace adjusted. Pad the outside of the knee at night if you sleep with the leg rolled out.
Alongside that:
- An ankle-foot orthosis holds the foot up so you can walk without catching your toe, and it prevents falls while the nerve recovers. Choosing a foot drop brace.
- Physical therapy keeps the ankle from stiffening into a fixed drop, strengthens what still works, and retrains balance.
- Surgical decompression is considered when the nerve is deteriorating rapidly, when there has been no improvement after about three months, or when a cyst or an open injury is the cause.
- Tendon transfer is an option much later, where the nerve has not recovered and the foot drop is permanent.
For the stretching and strengthening itself, see foot drop exercises.
Cleveland Clinic notes that recovery from surgery itself takes about three to four months, with activity limits in the first six weeks. That is recovery from the operation, separate from the nerve’s own regrowth.
Recovery: what to expect, and when
Recovery depends on what the pressure did. Mild compression bruises the insulation around the nerve while leaving the fibers intact, and that recovers over days to weeks. Where fibers have died back, they regrow from the point of damage at roughly a millimeter a day, about an inch a month, so recovery is measured in months, and it may be incomplete. Many pressure-related peroneal palsies do improve without surgery. Foot drop after a knee dislocation is the exception, with a poor outlook for long-term nerve function.
Three things help you and your clinician judge progress: whether the numb area is shrinking, whether the Tinel sign is advancing further down the leg, and whether any flicker of movement has returned in the muscles that lift the foot. How nerve recovery works generally.
When it is urgent
- Foot drop that appears suddenly, especially with back pain, numbness around the groin, or bladder or bowel trouble: emergency care.
- Foot drop that is getting worse over days rather than better.
- Foot drop after a knee injury, dislocation or surgery: tell the surgical team promptly.
- A numb foot with a wound, or a foot that becomes warm, red and swollen without an obvious injury.
Common questions
Can crossing your legs really cause foot drop?
Yes. The nerve lies against bone at the outside of the knee with little padding, and sustained pressure there is a well-recognized cause. It is more likely in people who are thin, who have recently lost weight, or who sit with one leg crossed for long periods.
How long does peroneal nerve recovery take?
Mild compression injuries can settle within days to weeks. Where nerve fibers have been lost, regrowth runs at about an inch a month, so several months is normal and recovery can be partial. Decompression is usually considered if there has been no improvement by about three months.
Is peroneal neuropathy the same as foot drop?
No. Foot drop is a symptom and peroneal neuropathy is one of its causes. The signal can be interrupted in the lower back, along the sciatic nerve, at the knee, or in the muscle itself, and treatment depends on which.
Does the nerve problem cause numbness in both feet?
No. This nerve serves one leg, so symptoms are one-sided. Numbness in both feet, starting at the toes and creeping upward, is a length-dependent neuropathy and has a different list of causes.
Is the peroneal nerve the same as the peroneal tendon?
No, though the names cause endless confusion. The peroneal tendons run behind the outer ankle bone and can be torn or inflamed. The peroneal nerve is a nerve, and its problems are weakness and numbness rather than local ankle pain.
Related reading
Foot drop: finding the level · Foot drop braces · Nerve conduction study and EMG · Numb feet · Nerve pain in the foot · Back nerve pain versus neuropathy
For attorneys: Dr. Biernacki reviews foot drop and peroneal nerve cases as an expert witness. Patients do not need this page.
Sources and further reading: Lezak B, Massel DH, Varacallo MA, Peroneal nerve injury, StatPearls, 2024, on how common the injury is, its causes, examination findings, indications for decompression and outcomes. Cleveland Clinic, peroneal nerve injury, on what the nerve does, diagnosis, braces and recovery after surgery. Nadi M, Dabbas W, Das JM, Peripheral nerve injury, StatPearls, 2026, on recovery from compression injuries and the rate of nerve regrowth. NINDS, peripheral neuropathy.
This page is general education and is not a diagnosis or a treatment plan. Clinical review by Dr. Biernacki is pending; the review date will be shown here once complete.
For our Michigan neighbors
Catching your toe
on one side?
A foot drop needs its level found rather than just a brace, and the examination that finds it takes minutes. Dr. Biernacki’s Michigan practice can do that.
Everywhere else, take this page to your own clinician.
Dr. Tom Biernacki, DPM, FACFAS is a double board-certified foot and ankle surgeon (ABFAS and ABPM) and a Fellow of the American College of Foot & Ankle Surgeons. He is the founder of Balance Foot & Ankle in Howell and Bloomfield Township, Michigan, where peripheral neuropathy, diabetic foot risk and loss of protective sensation are part of his weekly clinic. His patient education videos have drawn more than 950,000 subscribers on YouTube. Managing Neuropathy is written by its editorial team under his direction, to put the explanation he gives in the exam room in front of the people who cannot get to one — including when a product is worth buying and when it is not.