Diabetes mellitus (DM) is a chronic, demanding metabolic disease that affects individuals, their families, and society worldwide (1). Approximately 463 million people suffer from DM in the world, and this number is expected to rise by 25% by 2030 (2). Among all complications, diabetic foot ulcers (DFUs) are one of the serious and refractory complications of DM. The latest definition of DFUs refers to infection, ulcer, or destruction of foot tissue caused by lower limb neuropathy and/or peripheral arterial disease in patients with DM (3). Studies have found that the prevalence rate of diabetic foot is 4%–10%, the annual population-based incidence rate is 1.0%–4.1%, and the lifetime incidence rate of diabetic patients may be as high as 25%, which brings a heavy economic burden to patients and their families (4). Patients suffering from DM account for almost 60% of all whole-limb amputations (5). Among these, heel ulcer is one of the severe complications of patients with diabetes, which poses a high risk for foot infection and amputation, especially in patients with peripheral arterial disease (PAD). In this case report, we demonstrated the treatment of large ischemic ulcers for the first time in a diabetic patient.

Heel ulcer and ischemia are both predisposing factors for major amputation in diabetic foot patients, and the combination of these two factors increases the risk of this amputation to 20%, which is much higher than that of non-heel ulcer (6.9%) or non-ischemia ulcer (<5.1%) (8). In this case, the overall treatment goal was designed to improve blood supply to her diseased lower extremities and close the ulcer. First of all, we developed a set of treatment procedures for these patients (Figure 3), which were implemented in four stages: to revascularize the occluded large vessels of the affected lower limb, to improve the local blood supply of the ulcer, to debride and repair the ulcer, and to remodel the closed ulcer. If the target vessels leading to the heel, namely, the posterior tibial and peroneal arteries, are successfully reconstructed, which could improve the local blood supply, the overall survival rate of the free flap grafted to this site can reach 73%, and the limb salvage rate of the patient can be greatly increased (9, 10).

Under the guidance of the concept of “angiosome”, wound-oriented revascularization surgery is very important for ulcer healing and limb rescue (11–13). In this patient, the ulcer was located in the middle posterior aspect of her right heel, and the preoperative angiography confirmed long segment occlusion of the inferior segment of her right superficial femoral artery with segmentary severe stenosis. The posterior tibial artery and peroneal artery of her right lower extremity should be opened theoretically. However, as shown in Figure 1C, the anterior tibial artery, the peroneal artery including the posterior communicating branch, and part arterial arch of the foot were re-opened successfully, but the posterior tibial artery failed to be recanalized. Because the posterior communicating branch of the peroneal artery can compensatively supply blood to the posteromedial heel of the heel, thereby overcoming the adverse effects of the unsuccessful recanalization of her posterior tibial artery, it was believed that the patient still has the possibility of further complex surgeries to repair the wound at this time.

Studies have shown that as skin oxygen tension increases and carbon dioxide pressure decreases progressively for several weeks after a successful percutaneous transluminal angioplasty (PTA), the likelihood of ulcer healing increases dramatically. Therefore, the best time for surgical wound management should be 3–4 weeks after successful PTA revascularization and 1–2 weeks after bypass revascularization (14, 15). Note that during this period, local infection of the wound may worsen following the gradual recovery of blood flow, which needs much more observation and even debridement in advance if necessary. This patient experienced a waiting period of approximately 4 weeks after the vascular intervention, until the blood supply to the injured heel was restored, and the granulation tissue at the base of the wound was bright red and bleeding after scraping.

The following repair process for diabetic foot wounds is a combination of a series of medical methods, which is complicated. As a core component of traditional DFU treatment, debriding the wound not only removes inactive bone or soft tissue that may pose a risk of bacterial colonization and infection but also effectively repairs the wound to the acute stage or hemostasis/coagulation stage, which is conducive to its later healing (16). Some appropriate methods from the four-layer “pyramid” techniques of repairing soft tissue include negative pressure wound therapy/primary closure, local random flaps/skin grafting/bioengineered tissue alternatives, pedicle flaps/local muscle flaps, and free tissue transfer to cover the ulcer (17). Among them, pedicle flaps/local muscle flaps and free tissue transfer are the most difficult and risky and have high technical requirements for the operator, but they are still increasingly used in the treatment of diabetic foot ulcers because of their high effectiveness (18). With the restoration of local blood supply to the heel by recanalizing the peroneal artery successfully, the heel ulcer of this patient was cleaned clearly and closed with a highly challenging ultra-microsurgical peroneal artery perforator flap completely (Figure 2).

It is generally known that wound healing is the beginning of its basal tissue remodeling phase. During the healing process of diabetic foot wounds, irregular or irregularly arranged collagen fibers are gradually replaced by newly synthesized, more regular, and elastic collagen fibers until the original scar tissue on the wound becomes soft, has a lighter color, and becomes smooth and orderly. The entire wound remodeling process can last for months or even years until the tensile strength of the tissue within the wound is restored as much as possible. We followed up the patient approximately 7 weeks after the operation, and the wound was completely healed (Figure 2G). Moreover, offloading treatment at the wound-healing stage is very important for a DFU patient (19). The female patient was given adequate offloading therapy, such as non-weight bearing for up to 8 weeks after flap transplantation. Ultimately, the patient was able to walk gently with a well-healed flap at the 12th week and with full weight bearing at the 24th week.

This case report demonstrates that the management of large ischemic heel ulcers in diabetic patients has its particularity. The diagnosis of diabetic foot requires not only evaluation for ulceration, ischemia, and infection but also differentiation from other causes of heel ulcers. Subsequently, this type of ulcer should be treated in stages according to a certain sequence, as shown in Figure 4, to assess and revascularize the occluded large vessels of the affected lower limb, to improve the local blood supply of the ulcer, to debride and repair the ulcer, and finally to remodel the closed ulcer using flap surgery. Among them, the opening of at least one target blood vessel in the heel is the premise, the successful transplantation of the skin flap to cover the wound is the key, and offloading measures such as walking without weight-bearing are also very important in the later stage. In conclusion, as one of the risk factors of major amputation, massive ischemic heel ulcer needs to be carefully diagnosed and treated according to a special procedure.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Written informed consent was obtained from the patient for publication of this report. Written informed consent was obtained from the individual(s) for the publication of any identifiable images or data included in this article.

YDC was responsible for study conception and design. HY wrote the first draft of the manuscript. YCC, AP edited the manuscript. WW, DJ, LL, WY reviewed the last version of the manuscript. All authors contributed to the article and approved the submitted version