Most plantar forefoot ulcers in diabetes are pressure injuries. They form where repetitive mechanical stress concentrates on insensate tissue, and they return to the same place when that stress is never actually removed. Casts, walkers and custom footwear redistribute pressure, but they do not change the anatomy generating it. When a tight calf drives load into the forefoot, lengthening the triceps surae complex treats the cause rather than the consequence. This article reviews the published evidence on Achilles tendon lengthening and gastrocnemius recession in the diabetic foot.
Why Ankle Equinus Matters in the Diabetic Foot
Ankle equinus is limited ankle dorsiflexion, conventionally defined as less than about 10 degrees with the knee extended and flexed. In diabetes it is common, and it is thought to arise largely from stiffening of the gastrocnemius-soleus complex and Achilles tendon. Tagoe, Reeves and Bowling, writing in Diabetes/Metabolism Research and Reviews, describe equinus as the mechanical basis for elevated forefoot pressures in this population and the rationale for surgical lengthening.
The association is substantial. In a cohort reported by Meshkin and colleagues in the Journal of Foot and Ankle Surgery, equinus contracture carried roughly a threefold association with diabetes and a fourfold association with plantar foot ulceration. Equinus has also been implicated in the deforming forces that contribute to Charcot neuro-osteoarthropathy, which is why tendon lengthening is sometimes performed as an adjunct during Charcot reconstruction.
Where Surgical Lengthening Sits in the Offloading Pathway
Surgical lengthening is not a first-line treatment. The 2023 International Working Group on the Diabetic Foot (IWGDF) offloading guideline, authored by Bus and colleagues, is explicit about sequence: a non-removable knee-high offloading device is the first choice for a neuropathic plantar forefoot or midfoot ulcer. Only when such non-surgical offloading fails to heal a plantar forefoot ulcer does the guideline advise considering Achilles tendon lengthening, metatarsal head resection, joint arthroplasty or metatarsal osteotomy. The procedure is positioned as a rescue and durability strategy for the recalcitrant or repeatedly recurring wound, not as an alternative to casting.
What the Outcome Data Show
The systematic review and meta-analysis underpinning the IWGDF guideline, led by Lazzarini and colleagues, found that Achilles tendon lengthening combined with an offloading device likely increases healing compared with the device alone (risk ratio 1.10, 95% CI 0.97-1.27), and likely increases sustained healing. The same analysis found that the procedure likely increases new heel ulcers — the trade-off that defines this operation. Certainty of evidence was low to moderate, and the estimate rests on a single small randomised trial of 64 patients.
Observational series fill in the clinical picture. Meshkin and colleagues reviewed 91 neuropathic patients undergoing percutaneous tendo-Achilles lengthening without concomitant tendon procedures. At a mean follow-up of 31.6 months, 78.6 percent of wounds healed at a median of 12.9 weeks. However, 43.9 percent experienced ulcer recurrence at a mean of 12 months, and 13 percent developed a transfer lesion at a mean of 16.6 months. The authors concluded that a repeat lengthening procedure may be required at around a year.
Less aggressive lengthening appears to fade faster. Terwogt and colleagues, reporting in Foot & Ankle Specialist, followed 20 proximal medial gastrocnemius release procedures in 14 patients with plantar diabetic foot ulcers. Ninety percent achieved wound closure within four weeks, but half recurred at a mean of 9.2 months alongside recurrence of gastrocnemius shortening, and most of those patients went on to a second procedure. The authors judged proximal medial release insufficient for long-term control and suggested a more distal gastrocnemius release or percutaneous Achilles lengthening where durable correction is needed.
Complications and the Overcorrection Problem
Tagoe and colleagues summarise the principal hazards: tendon rupture, overcorrection, and the relatively poor blood supply of the Achilles tendon itself. Over-lengthening weakens plantarflexion and can produce a calcaneal gait pattern that shifts load posteriorly, which is the mechanism behind the new heel ulcers seen in the trial data. Because of rupture risk, the gastrocnemius aponeurosis has been proposed as an alternative lengthening site, and postoperative protocols typically call for reduced loading and protected range of motion in the first week, followed by graduated reloading to restore tendon strength.
Patient Selection
Ramanujam and Zgonis, reviewing surgical correction of the Achilles tendon in Clinics in Podiatric Medicine and Surgery, emphasise that the procedure is chosen against a specific deformity rather than against a wound in general. Documented equinus on clinical testing, a plantar ulcer unresponsive to appropriate offloading, adequate perfusion and controlled infection are the practical prerequisites. Where the driver of pressure is bony rather than tendinous — a plantarflexed first ray, cavovarus alignment or hallux rigidus — lengthening alone is unlikely to solve the problem, and the literature describes sequential, combined approaches for these cases.
Clinical Summary
Ankle equinus is a common and correctable contributor to plantar forefoot ulceration in diabetes. Achilles tendon lengthening and gastrocnemius recession likely improve healing and sustained healing when added to standard offloading for recalcitrant plantar forefoot ulcers, but the effect is not permanent: recurrence rates of 40 to 50 percent within roughly a year are reported across series, and a meaningful minority develop transfer or heel lesions. The evidence base remains limited to one small randomised trial plus observational cohorts, so these procedures are best understood as an escalation step within a structured offloading pathway, applied to patients with demonstrated equinus, rather than as a routine substitute for non-removable offloading.
References
- Bus SA, Armstrong DG, Crews RT, Gooday C, Jarl G, Kirketerp-Moller K, Viswanathan V, Lazzarini PA. Guidelines on offloading foot ulcers in persons with diabetes (IWGDF 2023 update). Diabetes/Metabolism Research and Reviews. 2024;40(3):e3647.
- Lazzarini PA, Armstrong DG, Crews RT, Gooday C, Jarl G, Kirketerp-Moller K, Viswanathan V, Bus SA. Effectiveness of offloading interventions for people with diabetes-related foot ulcers: A systematic review and meta-analysis. Diabetes/Metabolism Research and Reviews. 2024;40(3):e3650.
- Tagoe MT, Reeves ND, Bowling FL. Is there still a place for Achilles tendon lengthening? Diabetes/Metabolism Research and Reviews. 2016;32(Suppl 1):227-231.
- Meshkin DH, Fagothaman K, Arneson J, Black CK, Episalla NC, Walters ET, Evans KK, Steinberg JS, Attinger CE, Kim PJ. Plantar Foot Ulcer Recurrence in Neuropathic Patients Undergoing Percutaneous Tendo-Achilles Lengthening. The Journal of Foot and Ankle Surgery. 2020;59(6):1177-1180.
- Terwogt SFJ, Brekelmans W, Bénard MR, van Laar W. Proximal Medial Gastrocnemius Release in the Treatment of Plantar Diabetic Foot Ulcers: A Case Series. Foot & Ankle Specialist. 2025 (published online ahead of print).
- Ramanujam CL, Zgonis T. Surgical Correction of the Achilles Tendon for Diabetic Foot Ulcerations and Charcot Neuroarthropathy. Clinics in Podiatric Medicine and Surgery. 2017;34(2):275-280.
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