Most diabetic foot ulcer research has focused on the plantar forefoot, where neuropathy and repetitive pressure under the metatarsal heads produce a predictable pattern of injury. Heel ulcers are different. The heel carries high loads, has thin soft tissue over bone, is exposed to shear and prolonged pressure during bed rest, and is frequently affected by arterial disease. Evidence for how best to manage them is limited, and several recent studies show why clinicians treat them with particular caution.
Why the Heel Is a Distinct Problem
Heel ulcers arise through more than one mechanism. Neuropathic patients may develop plantar heel ulcers from walking, while patients with ischemia, reduced mobility, or hospitalization may develop pressure-related heel wounds. Because there is little soft tissue between skin and calcaneus, a heel wound can extend to bone quickly. In a retrospective review of ischemic foot wounds treated with pedal bypass or endovascular tibial intervention, Mohapatra and colleagues (2018) found that 12.1% of 380 wounds were located at the heel, and 10.9% of those showed evidence of calcaneal osteomyelitis. Patients with heel wounds were also more likely to have diabetes and renal insufficiency than patients with forefoot wounds.
Outcomes: Similar Healing, Worse Survival
In that same cohort, published in the Annals of Vascular Surgery, 43.1% of wounds healed within one year, with no significant difference between heel and other locations, and the one-year major amputation rate (17.8%) did not differ by wound location. However, amputation-free survival was markedly lower for heel wounds: 45.7% at one year and 17.6% at three years, compared with 66.2% and 44.0% for forefoot wounds. The authors concluded that heel wounds mark a patient population with higher mortality, a reminder that a heel ulcer often reflects advanced systemic disease and not only a local pressure problem.
Amputation risk in hospitalized patients has also been studied. Moon and colleagues (2019, Advances in Wound Care) reviewed 117 hospitalized patients with hindfoot ulcers at a single diabetic wound center. Of these, 89% healed without major amputation and 11% healed with major amputation. Pulmonary disorders, a higher erythrocyte sedimentation rate, and a lower total iron-binding capacity were independently associated with major amputation. This is a single-center, retrospective study, so the associations should be viewed as hypothesis-generating rather than definitive.
What Trials Show About Offloading
Offloading is the cornerstone of ulcer care, but the evidence base for the heel is thin. The systematic review by Lazzarini and colleagues (2020, Diabetes/Metabolism Research and Reviews), which informed the IWGDF offloading guideline, identified only low-quality evidence for plantar heel ulcers: one small randomized trial with a 16-patient rearfoot subgroup suggested that total contact casts healed ulcers faster than therapeutic footwear (69 versus 107 days), but the trial had a high risk of bias and reported no statistical test. For non-plantar ulcers, the authors described the evidence as practically non-existent.
The largest trial to date is the UK HEELS trial (Jeffcoate and colleagues, 2017, Health Technology Assessment). It randomized 509 adults with diabetes and a heel ulcer from 35 foot services to an individually moulded fibreglass heel cast plus usual care, or usual care alone. By 24 weeks, 44% of the cast group and 37% of the usual-care group had healed, a difference that was not statistically significant (odds ratio 1.42, 95% CI 0.95 to 2.14). Time to healing, pain, and recurrence did not differ significantly, and the cast was not considered cost-effective within the health service setting studied.
What Current Guidelines Recommend
The IWGDF 2023 offloading guideline (Bus and colleagues, on behalf of the International Working Group on the Diabetic Foot) addresses this gap with cautious wording. For plantar rearfoot ulcers, it suggests considering a non-removable knee-high offloading device over a removable one to promote healing, a conditional recommendation based on very low-certainty evidence. For non-plantar ulcers, it recommends using a removable offloading device, footwear modifications, toe spacers, orthoses, or digital flexor tenotomy, chosen according to the type and location of the ulcer; this is a strong recommendation, again based on very low-certainty evidence. In practice, this means that the choice of device for a heel ulcer should be individualized, taking into account perfusion, infection, mobility, and the patient’s ability to use the device safely.
Key Takeaways
Heel ulcers in diabetes are associated with exposure of bone, frequent coexisting arterial disease and renal impairment, and worse long-term survival than forefoot ulcers, even when short-term healing and amputation rates are similar. The best available randomized trial found no significant healing benefit from a heel-specific fibreglass cast, and guideline recommendations for heel and other non-plantar ulcers rest on very low-certainty evidence. Careful assessment of perfusion and bone involvement, together with individualized pressure relief, remains the evidence-informed approach, and high-quality trials with location-specific reporting are still needed.
References
- Bus SA, Armstrong DG, Crews RT, et al. Guidelines on offloading foot ulcers in persons with diabetes: IWGDF 2023 update. International Working Group on the Diabetic Foot, 2023.
- Lazzarini PA, Jarl G, Gooday C, et al. Effectiveness of offloading interventions to heal foot ulcers in persons with diabetes: a systematic review. Diabetes/Metabolism Research and Reviews. 2020;36(S1):e3275.
- Jeffcoate W, Game F, Turtle-Savage V, et al. Randomised controlled trial of fibreglass heel casts for heel ulcers in diabetes (HEELS). Health Technology Assessment. 2017;21(34).
- Mohapatra A, Henry JC, Avgerinos ED, et al. Heel wounds predict mortality but not amputation after infrapopliteal revascularization. Annals of Vascular Surgery. 2018;51:78-85.
- Moon KC, Kim KB, Han SK, Jeong SH, Dhong ES. Risk factors for major amputation on hindfoot ulcers in hospitalized diabetic patients. Advances in Wound Care. 2019;8(5):177-185.
Comments
