Nerve grafting for leg, ankle and foot nerve injuries

What a nerve graft does

If a nerve is cut and the two ends can be brought together without tension, they are sewn directly. If a piece of the nerve is missing, pulling the ends together would stretch the nerve and reduce its chance of recovery. A graft supplies a scaffold that guides the regrowing fibres across the gap. Nerve fibres grow into the graft and through it to the target. The general principles of repair are in nerve repair and reconstruction.

When grafting is considered

• A cut nerve with a gap, for example after a deep laceration or an operation. See nerve laceration.
• A neuroma in continuity or a scarred segment that has to be cut out, leaving a gap.
• Reconstruction after a painful neuroma is removed, when both ends of the nerve can be found. In a study of 12 people with painful lower-limb neuromas, a processed donor nerve was used to reconstruct the nerve in 5 of them, and in the others to lengthen the nerve and place it in muscle.^[4] A separate multicentre registry of 21 people with upper-extremity neuromas reported that pain improved in 80% of repairs and meaningful sensory recovery occurred in 88%.^[3]
• Injuries to a motor nerve, although grafts have a lower success rate for the peroneal nerve than nerve release or end-to-end repair (49.0% reached a good motor grade in one pooled analysis, compared with 81.4% and 78.8%). Different injuries are involved in those groups.^[5]

The graft choices

• Autograft: a segment of your own sensory nerve, most often the sural nerve from the back of the calf. It leaves numbness where it was taken.^[2]
• Processed nerve allograft: processed donor nerve tissue, which avoids taking a nerve from your own leg.^[1]
• Conduit: a hollow tube that guides regrowth across a short gap.^[1]

A 2023 systematic review and meta-analysis of nerve gap repair compared allografts, autografts and conduits. Rates of meaningful recovery were similar for autografts and allografts, and lower for conduits in short sensory gaps, with more pain-related complications.^[1]

The donor site: what you give up

The sural nerve is the most commonly harvested nerve autograft.^[6] It supplies the skin along the outer edge of the foot and ankle, so taking it leaves a strip of numbness. A pooled analysis of nine studies (240 patients) found that 87.2% reported sensory loss, 25.6% reported pain, 22.2% reported cold sensitivity and 10% reported functional impairment. The area of numbness generally shrank over time. Sparing the upper part of the nerve was linked to less sensory loss and pain than harvesting at the back of the knee.^[2] A separate review of 478 procedures reported chronic pain in 19.7% wound infections in 5.7% and other wound complications in 7.8%, and it concluded that alternatives should be considered when they are suitable.^[6] This is one reason surgeons weigh a donor graft against a processed allograft.

Timing and results

Outcomes depend on the length of the gap, the nerve, the time since injury, and patient factors such as age. In traumatic peroneal nerve injuries, shorter graft length and shorter time to surgery were linked to better outcomes.^[5] Regrowth is slow. Nerve fibres advance about a millimetre a day, so recovery is measured in months.^[7]

Risks

Risks include infection, wound-healing problems, a neuroma at the repair, incomplete recovery of feeling or strength, pain at the donor site, and the need for further surgery. See revision nerve surgery for what happens when a first operation has not settled the problem.

Is a graft right for you?

Whether a graft, a direct repair, a nerve transfer or no surgery is the right choice depends on the nerve, the gap, the timing and your goals. Read about nerve transfer as an alternative when a motor nerve cannot be bridged. Dr. Ozturk performs this procedure for appropriate patients, and an evaluation is how to find out whether it fits your situation.

When to seek care

Consider an evaluation if you have numbness, burning or weakness after a cut or an operation that has not improved over several weeks.