Painful scars and nerve pain after leg, ankle or foot surgery

When a scar hurts because of a nerve

Every incision crosses tiny skin nerves. Most people notice some numbness around a scar that gradually improves. In some people the pain is out of proportion. It may feel like burning, electric shocks, or an unpleasant response to light touch, clothing or a shoe rubbing. Nerve scarring can cause severe pain and dysfunction.^[2]

There are three common patterns:

• A cut nerve that formed a neuroma, a tender knot beneath the scar. See painful neuroma of the foot, ankle and leg.
• A nerve caught in scar tissue, where the scar tethers the nerve, so it is pulled or squeezed when the foot moves. In these cases the nerve’s course or function is altered by local scar.^[1]
• A nerve stretched or bruised by the operation, sometimes settling by itself and sometimes not.

Where it happens

Scars on the top or outer side of the ankle and foot lie over the superficial peroneal nerve and its branches, and in one study 21% of people who had ankle fracture surgery, compared with 9% of those treated in a cast, had painful symptoms from an injury to that nerve.^[4] Scars on the outer heel and foot may involve the sural nerve, scars on the inner ankle may involve the tibial nerve branches and the saphenous nerve, and knee scars may involve the infrapatellar branch of the saphenous nerve. For that, see nerve pain after knee replacement. More on operations and injuries is in nerve pain after surgery or injury.

Why it can be hard to sort out

Chronic pain after foot and ankle surgery is not well defined. A scoping review found only seven randomized trials of pain management after elective mid- and hindfoot and ankle surgery, most followed patients only for two days, and one assessed pain at six months. The authors described an overwhelming lack of evidence on chronic postsurgical pain after these operations.^[3] That does not mean the pain is not real. It means the research has not caught up.

How it is evaluated

Your clinician will ask about the timing, examine the scar and the surrounding skin, and tap along the nerve path to find a trigger spot. The goal is to tell apart nerve pain from other post-operative causes, such as stiff joints, tendon problems, retained hardware and infection. Ultrasound or MRI can show a neuroma or a tethered nerve, and nerve studies and diagnostic injections are arranged with another specialist.

Treatment

• Time and simple measures. Scar massage, desensitization and padding may help while a nerve settles.
• Medicines and injections. Medicines for nerve pain are described in non-surgical treatment. Injections can reduce pain around a nerve in some people.
• Neurolysis (nerve release). Freeing a nerve from scar can help in entrapment syndromes and where local scar has altered the nerve’s course.^[1] See nerve decompression.
• Neurectomy. In selected cases, the painful nerve is divided. It is an option where numbness is an acceptable trade-off for a painful sensation, or after a release has failed.^[1]
• Nerve repair or reconstruction, which may improve pain by guiding regrowing fibres past the neuroma.^[1] See nerve repair.
• Revision surgery and nerve wrapping. Symptoms can return after a first decompression in up to 25% of cases. In a review of 11 case series (114 patients), wrapping the nerve with a vein, collagen or amniotic membrane gave improvement, although pain was the most common residual symptom (46%). No single wrap has been shown to be superior.^[5] A nerve wrap aims to prevent new scar from re-tethering the nerve.^[2] See revision nerve surgery.

Setting expectations

Results vary. Freeing a nerve or treating a neuroma does not always end the pain, and surgery has its own risks, including infection and new scarring. Where a painful neuroma is treated, the aim is meaningful improvement in pain rather than a promise that it will disappear.

When to seek care

Consider an evaluation if a surgical or injury scar has burning, shocking or hypersensitive pain that lasts more than a few weeks, or a trigger spot that shoots when touched.