Achilles Lengthening for Forefoot Ulcers That Keep Coming Back

A total contact cast is the standard way to heal an ulcer on the ball of the foot in people with diabetes, yet these ulcers often return.⁠^[3] When one keeps returning to the same spot, the question becomes what keeps pressing on it. Our page on surgery that takes pressure off ulcers covers the other tendon and bone procedures, and our guide to diabetic foot ulcers covers the whole healing plan.

Why a tight calf keeps pressing on the same spot

With each step, your shin tips forward over the foot. When the calf muscles and Achilles tendon are tight, the ankle can’t bend upward far enough (a condition called equinus), so the heel lifts early and more of your weight rolls onto the ball of the foot; diabetes itself can change the fibers of the Achilles tendon and make it tighter.⁠^[4]

Among 1,666 people with diabetes seen at one clinic, 10.3% had equinus, and they were nearly three times as likely as the others to have high pressure under the foot.⁠^[5] With numb feet, the soreness that would make you shift your weight never arrives. Lost feeling and high pressure on the sole are both implicated in how these ulcers start.⁠^[3]

A cast or knee-high device lowers that pressure only while you wear it. Surgery changes the structure and function of the foot, so it keeps working on the days you aren’t in a boot.⁠^[2]

Swipe sideways to see the whole drawing.

Who it suits

The 2023 guideline from the International Working Group on the Diabetic Foot (IWGDF) suggests considering Achilles lengthening, together with an offloading device, for a nerve-related ulcer under a metatarsal head (the ball of the foot) when non-surgical offloading hasn’t healed it. The recommendation is conditional and rests on moderate-certainty evidence.⁠^[2] In the panel’s view, it fits a foot held in equinus, and it is also an option when an ulcer has moved to another metatarsal head after earlier bone surgery on the forefoot.⁠^[2]

Good candidates usually have:

• An ulcer that stalled or returned despite good offloading. The first choice is a non-removable knee-high device such as a total contact cast,⁠^[2] and surgery is the next step when that hasn’t been enough.
• A measurably stiff ankle. Everyone in the main trial could bend the ankle upward 5° or less.⁠^[1] A Foot and Ankle Surgeon checks that motion with the knee straight and then bent, to tell whether the tendon or the calf muscle is tight, or bone is blocking the joint.⁠^[4] We take X-rays at the practice when they’re needed.
• Enough blood flow to heal. Surgical offloading is not advised when blood flow to the foot is severely reduced.⁠^[2] We start with noninvasive circulation testing at our practice; see circulation tests for foot wounds and why toe pressures can tell more than ankle pressures.
• Some feeling left in the heel. In one series, 47% of people with no feeling at all in the heel pad soon developed a heel ulcer, and the authors advised against the operation for them.⁠^[6]

If a probe reaches bone at the base of the ulcer, or an MRI shows infection in the metatarsal head, removing that bone is considered as well, sometimes alongside the lengthening.⁠^[2] See bone infection in the foot.

What the operation involves

The traditional technique is a triple hemisection: three partial cuts along the tendon, which can be made through small punctures in the skin (percutaneously) rather than an open incision.⁠^[7] One British team did it as an outpatient procedure on 96 feet, followed by six weeks of walking in a cast, and recorded no infections or wound problems from the operation.⁠^[8]

When the tightness comes mainly from the gastrocnemius, the main calf muscle that points the foot down, a gastrocnemius recession releases that muscle instead of the tendon; the evidence for it in forefoot and midfoot ulcers is more limited.⁠^[9] Our Center for Lower Extremity Surgery explains gastrocnemius recession (external site) in more detail.

Dr. Ozturk performs Achilles lengthening and gastrocnemius recession for the ulcers that need them. As a Foot and Ankle Surgeon who is also board certified in wound care (FAPWH), he follows the ulcer from the first visit through the operation until the skin has closed. Many people never need it; it is the step for an ulcer that keeps stalling or coming back.

What the research shows

Forefoot pressure falls soon after the operation, though part of that drop fades: in a randomized comparison, it fell 27% at first after lengthening, then rose again over the following months as the calf regained its push-off power.⁠^[10] Healing and staying healed held up.

• Fewer ulcers coming back. In the randomized trial, adding the lengthening cut the risk of a recurrence by 52% at two years.⁠^[1] Pooling two randomized trials, healing was about the same as with a cast alone, but a recurrence was less than half as likely.⁠^[3]
• Fewer repeat operations. When lengthening was added to wound closure surgery, recurrent ulcers needing another operation fell from 25% to 2%, and new sores elsewhere on the foot (transfer lesions) from 12% to 4%; the authors stress avoiding too much lengthening.⁠^[11]
• Fast healing in the right foot. In the British series of ulcers with good blood flow, 96% healed within about 10 weeks of the lengthening.⁠^[8]
• Not always a one-time answer. In a US series, 44% of healed ulcers came back at a mean of 12 months, and the authors noted that a second lengthening may be needed within about a year.⁠^[12]

The trade-offs

The main cost of Achilles lengthening is pressure moving to the heel. A systematic review of offloading treatments judged that it likely increases new heel ulcers.⁠^[13] Another review, of 490 percutaneous lengthenings, found a complication after 27.8% of them, including heel ulcers after 8%, and named over-lengthening, which leaves a heel-first walk, as a cause.⁠^[14]

Other risks:

• A tendon tear. The tendon tore in 10% of feet in one older series⁠^[6] and was found completely cut through in 4% in a newer one.⁠^[8]
• Weaker push-off for a while. Calf strength dropped after the operation and was back to its starting level by seven months, while the ankle kept its extra upward bend.⁠^[1]
• Falls and infection. The guideline panel counted possible increases in falls and infections, based on low-certainty evidence.⁠^[2]

The limits are real, too. The systematic review of offloading treatments rated the evidence for every treatment it assessed, surgical or not, as low to moderate certainty.⁠^[13] And the amount of lengthening has to be judged carefully: in one series, ulcers failed to heal or came back more often (33%) when the ankle still bent upward less than 10° afterward, while late heel ulcers appeared in 14% of feet that bent more than 15°.⁠^[6]

Recovery and keeping the ulcer closed

For the first week, the leg needs reduced loading and protected motion so the tendon doesn’t tear, followed by a gradual return to normal loading.⁠^[7] The foot stays protected in a cast or knee-high device until the ulcer has closed; in the main trial, that took a mean of 58 days.⁠^[1] We fit the device and show you how to get around safely, and our article on life in a total contact cast covers the everyday side of those weeks.

Once the skin has closed, prescribed footwear that lowers pressure on the sole while you walk helps keep the ulcer from coming back.⁠^[15] We fit therapeutic shoes and custom inserts; see offloading boots and protective footwear and keeping your foot in remission. At follow-up visits we also check the heel, where a new sore is the complication to watch for.

For an ulcer on the tip of a bent toe, a different small operation fits better: see flexor tenotomy for toe ulcers.

Common questions

Is Achilles lengthening a big operation?

In the main trial, it was done through small punctures in the skin,⁠^[1] and one team performed it as an outpatient procedure.⁠^[8] The bigger commitment is the weeks in a cast or boot afterward.

Can calf stretching do the same job?

Calf stretches are a standard treatment for a tight calf.⁠^[4] In people with diabetes and equinus, though, eight weeks of calf stretching made no meaningful difference to ankle motion or forefoot pressure in a randomized trial of 68 adults.⁠^[16]

Will it help an ulcer on my heel or toe?

Not a heel ulcer: after lengthening, pressure under the heel rose by about a third and stayed higher eight months later.⁠^[10] See heel ulcers and pressure injuries. For an ulcer on a flexible second to fifth toe, the guideline recommends releasing the toe’s flexor tendon instead.⁠^[2]

Can the ulcer still come back?

Yes. Lengthening lowers the risk without removing it; 38% in the trial had another ulcer by about two years.⁠^[1] Treating any new callus or blister early and wearing the right footwear still matter after surgery.⁠^[15]

What if my circulation is poor?

Then blood flow comes first. Surgical offloading isn’t advised when blood flow is severely reduced,⁠^[2] so we work with a vascular specialist to restore circulation before planning it.

The bottom line

A tight calf can keep pressing a forefoot ulcer into the ground long after a cast has done its work. For the right foot, meaning an ulcer under the ball of the foot that stalled or returned, a stiff ankle, enough blood flow and some feeling in the heel, Achilles lengthening is a small operation that helps the ulcer heal and lowers the chance of it coming back. It carries real risks, a heel ulcer above all, so it belongs in a plan with close follow-up and protective footwear.