Tibial transverse transport with corticotomy in the proximal tibia is an emerging new surgical technique for the treatment of severe chronic limb ischemic diseases such as diabetic foot ulcers. During distraction, neovascularisation and increased perfusion in the ulcerated foot accelerate healing and limb salvage and decrease recurrence [14]. In this study, we developed a novel osteotomy technique called triplanar osteotomy in the proximal tibia, followed by transverse transport, for the management of recalcitrant diabetic foot ulcers. Compared to conventional surgical therapy, triplanar osteotomy combined with TTT exhibited a higher rate of ulcer healing and a lower rate of amputation and recurrence at the 18-month follow-up.
Due to the hyperglycemic status of patients with diabetes, the pathophysiology of foot ulcers is characterized by neuropathic, vascular, and immune system disorders [20]. Oxidative stress in nerve cells and glycosylation of nerve cell proteins lead to neuropathy and further ischemia [21]. Moreover, endothelial cell dysfunction occurs after from hyperglycemia-induced changes in the peripheral arteries, leading to reduced vasodilation and increased vasocontraction [21, 22]. Additionally, immune function changes, including decreased healing response and increased apoptosis of immune response cells, are observed in patients with diabetic foot ulcers [22]. Thus, the treatment of diabetic foot ulcers should focus on not only angiogenesis and neurogenesis caused by surgical techniques, but also self-management, including glycemic control, home monitoring, and appropriate foot care. However, most conventional surgical therapies emphasize on peripheral percutaneous angioplasty and wound healing of foot ulcers, contributing to a high rate of recurrence, amputation, and even death [16, 23].
Our study showed that after treatment with TTT, neovascularisation and increased microcirculation occurred in the diabetic foot, which is consistent with the outcomes observed in animal studies [24, 25]. Yang et al. reported that increased endothelial progenitor cells were found in the wound following TTT management, confirming that transverse transport is beneficial for angiogenesis in the foot [25]. Meanwhile, immunomodulatory responses have been found to play an active role after TTT treatment, especially in the late stage of ulcer healing. M1 and M2 macrophages are the most prominent cells in the inflammation and proliferation phases of tissue repair [26, 27]. M1 macrophages are remarkably promoted to M2 by TTT, indicating a switch from inflammation to the proliferation phase of wound healing [28]. M2 macrophages release vascular endothelial growth factors to promote blood vessel formation and guide axonal regeneration [29]. Therefore, angiogenesis and neurogenesis mutually contribute to the resolution of inflammation and initiation of healing [30]. Additionally, the TTT procedure can also induce positive systemic responses by mobilising bone marrow-derived endothelial progenitor cells and mesenchymal stem cells to the ulcer area to promote histogenesis [31].
Different from the TTT technique reported previously [14], it is worth noting that a 6.5-cm by 1.5-cm triplanar osteotomy instead of a 5-cm by 1.5-cm corticotomy was performed in our study. To preserve and accelerate perfusion of the transported bone fragment as much as possible, and to increase the bone contact area after distraction, the medial margin of the tibia, rather than a vertical rectangle osteotomized in the center of the proximal medial tibia, was used as the base of the rectangle. In a recent study by Grüneboom et al., hundreds of capillaries, referred to as trans-cortical vessels (TCVs), were verified to originate in the bone marrow, cross cortical bone perpendicular to the shaft and connect to the periosteal circulation in human limb bone [32]. Furthermore, TCVs can mediate the recruitment of immune cells from the bone marrow to the circulation for host defense against inflammation [32, 33]. Hence, for minimally invasive incision and intact periosteum retention, triplanar osteotomy combined with transverse transport could induce the TCV system in the cortices to facilitate neovascularisation and immunomodulation. In addition, according to the hypothesis of ‘open window’ [15], triplanar osteotomy of the proximal tibia could also contribute to relieving bone marrow pressure, decreasing vasocontraction, and consequently improving microcirculation to foot ulcers.
The skin is normally weak immediately after an ulcer has healed, which is the period when patients think they no longer have a foot problem. Consequently, patients may not pay attention to follow-up podiatric care and warning signs of recurrence [34]. In accordance with the opinion of Armstrong et al.[7], we encouraged the patients in this study to ensure on good glycemic control, ongoing professional foot care at intervals of 1−3 months, appropriate-fitting footwear to relieve plantar pressure, and home-based foot care, including monitoring of foot skin temperature and other inflammatory signs to prevent ulcer recurrence.
This study has several limitations. It was a retrospective, nonrandomized study. Therefore, selection bias could have occurred. However, the patients in both groups were consecutively recruited by different surgeons using the same criteria, and these patients will stilled be observed to assess their long-term outcomes. Additionally, the number of patients was small and heterogeneous. Further studies in larger populations are necessary to confirm the benefits of this unique therapy.
In conclusion, our results indicate that proximal TTT is a useful treatment option for recalcitrant diabetic foot ulcers. Triplanar osteotomy not only increases the bone contact area after transport, which is beneficial for rapid bone healing, but also preserves the vascularisation of the bone fragment and substantially facilitates capillary angiogenesis during distraction. Such innovative therapy during the active phase of diabetic foot ulcers combined with a focus on improving care after healing of the ulcer can result in improved quality of life.