Wounds and problems after a toe or partial foot amputation

Why new problems can follow a partial foot amputation

A partial foot amputation is limb salvage in its own right: it removes only the part that can’t be saved, so you keep a foot to stand and walk on.⁠^[2] What it doesn’t change is what caused the first wound. Nerve damage that hides pain, and stiffness or deformity in the rest of the foot, are often still there.⁠^[1]

In 11 people with diabetes missing the big toe and part of its metatarsal bone, peak pressure was higher under the ball of the foot and the remaining toes than under their intact foot.⁠^[1] An ulcer that forms where the load has moved is called a transfer ulcer. The international guideline counts the changes left by an amputation as a foot deformity, like a bunion or a hammertoe.⁠^[3]

What to watch for at each level

Swipe sideways to see the whole drawing.

• The big toe or first ray. In a five-year Japanese study of healed diabetic foot ulcers, new ulcers after a big toe amputation formed more often on the neighboring toes of the same foot.⁠^[5]
• A smaller toe. The toes on either side can drift into the gap. After 24 second toe amputations in people with diabetes, followed for about three years, half the feet developed an ulcer on the side of a neighboring toe and 71% had a drifting big toe (hallux valgus).⁠^[6]
• Transmetatarsal or midfoot (Lisfranc or Chopart). These levels remove the toes and the tendons that lift them. One unproven theory is that the calf then pulls with less to balance it, so the foot slowly tips downward (equinus) and loads the end of the stump.⁠^[7] After a transmetatarsal amputation, ulcers that keep returning commonly stem from that pull or from extra bone that forms at the cut end.⁠^[4] At these levels, new ulcers tend to form at the operated site, sometimes late: about 19 months after a transmetatarsal amputation, on average, in one study.⁠^[5,7]

The incision, bone infection and nerve pain

Slow healing of the incision is common.⁠^[2] If yours is open or reopens, see surgical wounds that won’t heal. Warmth, redness or swelling around it can be the first sign of infection; see a red, hot, swollen foot.

An ulcer over a bone end can lead to bone infection: in one study, 47% of people with a late ulcer after a transmetatarsal amputation also developed osteomyelitis.⁠^[7] Even a small sore deserves prompt attention; see bone infection of the foot.

Pain in what remains of the limb can follow a partial amputation, not only a larger one. A common cause is a neuroma, a sensitive knot that forms at the end of a cut nerve.⁠^[8] The Lower Extremity Nerve Institute, our sister practice, treats neuroma pain after amputation (external site).

How we examine a foot after an amputation

For the highest risk group, the guideline advises checks every one to three months, an interval based on expert opinion. Each check looks for deformity and whether it is changing, stiff joints, excess callus, and early warning signs such as blisters, cracks and bleeding under the skin.⁠^[3]

At these visits we look at the skin over every bone end and along the scar, trim callus, and check sensation, pulses and ankle motion. We test circulation noninvasively at our practice (see circulation tests for foot wounds), and X-rays taken here show how the remaining bones line up.

Shoes, fillers and offloading come first

For a person with diabetes whose foot shape raises pressure, the guideline suggests considering extra-depth or custom-made shoes, custom insoles or toe orthoses. After a sole ulcer heals, it recommends shoes with a demonstrated pressure-relieving effect, worn indoors and outdoors.⁠^[3]

After minor amputations, custom toe fillers and foot orthoses improved walking speed and spread pressure more evenly; after amputations farther back, devices reaching above the ankle worked better. Much of this evidence comes from case reports.⁠^[9]

We fit therapeutic shoes and custom inserts and recheck them at visits, because inserts flatten over time. See offloading boots and protective footwear, and Ozturk Foot & Ankle’s page on diabetic foot care and therapeutic shoes (external site).

If a new ulcer opens, we clean and trim it at wound care visits, usually every week or two, and take pressure off it. For a neuropathic ulcer on the ball or middle of the sole, the offloading guideline’s first choice is a non-removable knee-high device.⁠^[10] For the ulcers that need one, we apply a total contact cast or a knee-high walker that can’t be taken off, and show you how to get around safely.

When surgery is the better fix

Shoes can cushion a pressure point, but they can’t change the bone or tendon that creates it. In people with diabetes and numb feet, when an ulcer under the ball of the foot doesn’t heal with non-surgical offloading, the guideline suggests considering Achilles tendon lengthening or removing or reshaping the bone beneath it, alongside an offloading device. For an ulcer at the tip or underside of a flexible curled smaller toe, it recommends releasing the tendon that curls it.⁠^[10]

• Achilles lengthening or a calf release for a stump pulled downward. In one series, returning ulcers at the end of a transmetatarsal amputation healed after 30 of 33 Achilles procedures (91%).⁠^[4] Another study found late forefoot ulcers in 35% of feet after a transmetatarsal amputation alone, versus 3% when the Achilles was lengthened at the same operation.⁠^[7] See offloading surgery.
• Removing a bone edge or spur that keeps pressing through the skin; see exostectomy.
• A tendon release for a flexible smaller toe that has started to curl, with an ulcer or a thick callus at its tip.⁠^[10,3]
• A planned revision when a short or unbalanced remnant keeps breaking down. In a review of 435 partial first-ray amputations in people with diabetes and neuropathy, about one in five later needed another amputation; on limited data, the authors suggested that a balanced transmetatarsal amputation from the start might serve patients better.⁠^[11] A second opinion can help you weigh this.

Dr. Ozturk, a Foot and Ankle Surgeon who is board certified in wound care (FAPWH), performs these operations, including revisions at the toe, ray, transmetatarsal and midfoot levels, for the feet that need them. The aim is the smallest operation that removes the pressure and keeps you walking.

Limits and risks

Surgery can lower the odds of another ulcer, but it doesn’t remove them. In one series, 16 of 28 people developed a new or returning ulcer after Achilles lengthening alone for ulcers after a transmetatarsal amputation.⁠^[12] Lengthening can also move pressure to the heel: studies that allowed early walking reported new heel pressure sores in 12–18%, and one study that kept the leg in a cast, off its feet, for four weeks reported 2.9%. In that study, 2 of 35 lengthened tendons ruptured; both healed with immobilization and rehabilitation.⁠^[7] These small studies of past patients give estimates, not certainties.⁠^[7,12]

Before any operation we check circulation; when it is reduced, we arrange a vascular specialist’s evaluation first (see peripheral artery disease).

Protecting both feet for the long run

In people with diabetes followed after a first amputation, the risk of another amputation on the same side was highest in the first six months, while the risk to the other leg rose steadily over the years.⁠^[13] In the Japanese study, a new ulcer on the other foot was the most common pattern (45% of cases).⁠^[5] Protect both feet, not only the scar. Keeping your foot in remission covers daily checks and long-term care.

When to seek care

See us within a day or two for any foot wound that isn’t healing, especially if you have diabetes.