18 Diabetic Foot Reconstruction

Joon Pio Hong

Summary

The treatment of diabetic foot ulceration is complex with multiple considerations and unfortunately often leads to amputation. A multidisciplinary approach along with an algorithm to manage and salvage diabetic foot ulcers from amputation is now a highly doable approach. Knowing the spectrum of care and reconstructive principles can prevent a diabetic foot infected with ulcers from amputation. Further understanding of supermicrosurgery and angiosome principles can extend the possibility for reconstruction in patients with severe ischemic diabetic foot.

diabetic foot – supermicrosurgery – angiosomes – diabetic foot reconstruction

18 Diabetic Foot Reconstruction

18.1 Introduction

According to the statistics given, approximately 3 to 4% of individuals with diabetes currently have foot ulcers or deep infections and 25% will develop foot ulcers sometime during their lifetime. ¹ ^, ² The risk of lower leg amputation increases by a factor of 8 once an ulcer develops. It is estimated that the age-adjusted rate of lower extremity amputation in diabetic patients is 15-fold that of nondiabetic patients. ³ Intractable diabetic foot ulcers can not only cause decreased physical, emotional, and social functions but also be a huge economic impact to the patient. ⁴ ^, ⁵ ^, ⁶ Furthermore, the 5-year mortality after major amputations may range from 39% to as high as 80%. ¹ ^, ⁷ ^, ⁸ These are the reasons why salvage for diabetic foot ulcers remains important as it will reduce economic burden and improve the quality of life. ⁸

Limb salvage from diabetic foot using the microsurgical approach showed similar success comparable to nondiabetic patients. ⁹ ^, ¹⁰ ^, ¹¹ ^, ¹² ^, ¹³ ^, ¹⁴ Meta-analysis of a systematic review of free tissue transfer in 528 diabetes patients in 18 studies showed flap survival of 92% and limb salvage rate of 83.4% over a 28-month average follow-up period. This study indicates that free tissue transfer in the management of nontraumatic lower extremity wounds in patients with diabetes may avoid amputations. ¹³ Free flaps and microsurgery technique now play an important role to salvage the limb from chronic ulcerations. A previous study showed that using microsurgery can achieve an overall limb salvage rate of 84.9% and 5-year survival of 86.8%. ⁸ There is no doubt that a well-vascularized free flap will enhance healing, quality of life, and survival chances.

In this chapter, we will focus on the clinical aspect of reconstruction and show a step-by-step approach on how to achieve reconstructive goals.

18.2 Attributes and Detriments

18.2.1 Attributes

Limb salvage using reconstruction is an alternative to amputation.
A multidisciplinary approach is essential in managing diabetic foot ulcers as diabetic patients have high comorbidity.
Once good vascular supply is secured, microsurgical or local reconstruction can be performed with reliable outcome.
The key is the status of the recipient artery and supermicrosurgery approach using small vessels can be considered.
Limb salvage not only leads to better quality of life but may also increase 5-year survival.

18.2.2 Detriments

A multidisciplinary approach is needed to adequately obtain good systemic condition and vascularity for reconstruction and may not be readily available.
Learning curve is needed to understand the algorithm of reconstruction and care.

18.3 Considerations

18.3.1 Multidisciplinary Approach and Spectrum of Care

The spectrum of diabetic foot disease may vary from asymptomatic to critically ischemic limb with unavoidable amputation. The spectrum of care for diabetic foot patients ranges from managing blood glucose, education on prevention, and managing small ulcers with good standard of care to using multiple new techniques and approaching with surgery (Fig. 18‑1). ¹⁵ The wide manifestation of symptoms is due to multifactor pathophysiology. The principal pathogenesis involves ischemia, neuropathy, and infection. The addition of external trauma, peripheral edema, and foot deformity may further increase the risk for diabetic foot ulceration. ¹⁶ They may act alone or synergistically to result in Charcot’s deformities, Achilles tendon contractures, ulcerations, necrosis, and gangrene. One must consider these pathologies and manage them in sequence in order to provide an efficient care for the foot. Treatment must begin with strict blood sugar control and nutritional support while aggressively managing the wound and infection to achieve closure of the defect. ¹⁷ In the cases with ischemic limb, vascular bypass or angioplasty may play a vital role to enhance circulation allowing further reconstruction of soft tissue and bone. ¹⁵

**Fig. 18.1** Treating diabetic foot requires a multidisciplinary care as the spectrum of care is very wide from managing blood glucose, education on prevention, and managing small ulcers with good standard of care to using multiple new techniques and approaching with surgery.

The nurse specialist or coordinator helps use the team recourses efficiently. After gathering general information about the patient and initial screening of the systemic and foot condition, the specialist would refer to an endocrinologist, nutritionist, and proper departments for further treatment and evaluation. There are four categories for initial foot evaluation: vascular, neuropathic, orthopaedic, and infectious wounds. ¹⁵ Multiple departments may be involved simultaneously to improve the patient’s foot condition. In the cases of emergent wound, a dedicated team needs to be notified immediately for emergency debridement and further clinical decision. This is the first and a major step to limit the spread of acute infection that may be critical in salvaging the diabetic foot. ¹⁸ Fig. 18‑2 shows the multidisciplinary algorithm for primary screening and initial treatment for wounds. ¹⁵

**Fig. 18.2** The multidisciplinary algorithm for primary screening and initial treatment for wounds is shown. Note the emergency track that requires immediate surgical attention. Once the problem resolved, routine follow-up is important to prevent further recurrence.

With the introduction of the multidisciplinary approach, the trend of management has shifted from major amputation to limb salvage. ¹⁹ Addressing the issues of perfusion, infection, wound treatment, off-loading, and bone surgery, we are able to increase the salvage rate. Similar with other reports, the major amputation rate for diabetic foot in our center has reduced significantly after a multidisciplinary approach and recently maintains to be about 3 to 4%. ²⁰ ^, ²¹ Although the indications for major amputation still exist and are often caused by multiple factors such as systemic sepsis, major tissue loss, significant comorbid factors, poor patient compliance, and non-reconstructable peripheral vascular disease, the goal remains the same: to salvage the limb under good clinical judgment. A nonhealing ulcer itself should not be considered an indication for amputation but be explored to solve the pathology behind it. ¹⁵ ^, ²² ^, ²³

18.3.2 Role of Microsurgery

Till recently, reconstruction with microsurgical techniques has been under debate. ¹⁵ This was due to the incorrect “myth” that patients with diabetes have an increased incidence of small-vessel disease that results in foot ulcers. Particularly, it was felt that patients with diabetes have arteriolar occlusive disease, which can cause ischemic lesions. This concept was first attributed to Goldenberg et al in 1959. ²⁴ They studied amputation specimens from patients with gangrene and concluded that diabetic patients have endothelial hypertrophy and proliferation in the smaller arteries, with complete occlusion of the lumen in several cases. But subsequent studies have failed to demonstrate increased arteriolar occlusive disease or endothelial proliferation. ²⁵ ^, ²⁶ ^, ²⁷ A thickening of the capillary basement membrane has been documented, but capillary narrowing or occlusion has not been documented. ²⁵ The same study showed that diabetics often have atherosclerotic occlusion of the tibial arteries, but the occlusive disease occurs mainly in the leg so that the arterial system in the foot is less involved. Also as the patient undergoes obstruction of major vessels, new collateral sprouts to maintain a relatively stable vascularity to the foot. ²⁸ Based on these studies, limb salvage from diabetic foot using microsurgical approach showed similar success in nondiabetic patients. ⁹ ^, ¹⁰ ^, ¹¹ ^, ¹² ^, ¹³ ^, ¹⁴ Meta-analysis of a systematic review of free tissue transfer in 528 diabetes patients in 18 studies showed flap survival of 92% and limb salvage rate of 83.4% over a 28-month average follow-up period. This study indicates that free tissue transfer in the management of nontraumatic lower extremity wounds in patients with diabetes may avoid amputations. ¹³ Free flaps and microsurgery technique now play an important role to salvage the limb from chronic ulcerations. ⁸ ^, ¹⁰ ^, ¹⁵ ^, ²⁹ ^, ³⁰

18.4 Surgical Algorithm

While the medical care for the patient with diabetic foot ulceration begins with stabilization of the patient’s systemic condition including blood glucose, the surgical care begins with debridement and control of infection. After the patient and the wound stabilized, further evaluation of the wound is made. Unless indicated for major amputation, the reconstructive algorithm is followed as shown in Fig. 18‑3. ¹⁵ If it is a simple wound with minimal or no vital structures exposed, conservative care with various treatments can be considered. If well granulating after wound preparation, skin graft or a small local flap can be performed. ³¹ Well-granulating wounds can be an indication for good vascularity. However, if healing is stalling, then further evaluation using transcutaneous oxygen pressure measurement (TcPO₂) or angiograms are warranted to evaluate the arterial flow and prepare for vascular intervention. The same evaluation and approach to ensure vascularity are needed for complex wounds waiting reconstructive procedure.

**Fig. 18.3** Reconstructive algorithm is shown. Depending on the defect and the available vascularity, reconstructive planning can be done accordingly.

18.4.1 Debridement

The first step of treatment for a diabetic foot wound is to evaluate, debride, and treat the infection. ³² Missing timely management will lead to amputations and longer hospital stays. ³³ If symptoms and sign of infection are clinically suspected, proper treatment must be provided without delay. If superficial infection is suspected without systemic infection, antibiotics treatment along with non–weight bearing of the foot should be ensued. Optimal management of a diabetic foot infection can potentially reduce incidence of major limb amputations and other related morbidities. All nonviable and infected soft tissue and bone should be excised during debridement. Milking along the proximal tendon can be helpful to identify and limit ascending infection. Tissue culture should be sent. Sufficient irrigation should follow after debridement to reduce bacterial count. ³⁴ Recent advance in technology introduced the hydrosurgery system and negative-pressure wound therapy allows achievement of cleaner and better granulation. ³⁵ ^, ³⁶

Understanding of vascular distribution of the foot angiosome is crucial in planning not only reconstruction but also debridement (Fig. 18‑4). ³⁷ When planning for reconstruction, one should avoid violating the angiosome territory even when designing a local flap that may lead to flap breakdown in patients with low vascular perfusion. ³⁸ Performing debridement according to the angiosome territory will enhance flap survival as the marginal vascularization from healthy surrounding angiosome territory occurs. ³⁹ Repetitive debridement should be performed as part of wound preparation for reconstruction while monitoring C-reactive protein (CRP) for possible hidden infections and using it as an index for possible infection after reconstruction. ¹⁵

**Fig. 18.4** The angiosome of the foot is shown. The six angiosomes of the foot and ankle are fed by the three main arteries. The anterior tibial artery becomes the dorsalis pedis artery supplying the dorsum of the foot. The posterior tibial artery (PTA) supplies the toes, the sole, and heel of the foot. The three main branches of the PTA supply distinct portions of the sole: the calcaneal branch to the heel, the medial plantar artery to the instep, and the lateral plantar artery to the lateral midfoot and the forefoot. The peroneal artery supplies the lateral border of the ankle and heel.

18.5 Soft-Tissue Reconstruction

Once an adequate debridement and reasonable vascular perfusion are achieved, in extensive and complex diabetic foot defects, reconstruction should be considered. It is crucial that one improve the vascularity of the leg thorough endovascular procedures or bypass graft depending on the patient’s status. Local flaps are useful when the patient has a good vascular status on the leg and foot. However, when the foot has compromised flow, the utilization of local flaps may breach the distal flow of the small collateral vessels especially the subdermal flow. ¹⁵ One must consider the vascular status as well as future flow where small collateral vessels may play an important role for distal circulation. Thus, the microsurgical approach may be considered for the following conditions: (1) lower limb defect that has not displayed any signs of granulation or healing despite adequate debridement or necrotic tissue and conservative treatment; (2) no significant systemic illness likely to be exacerbated by multiple operations and prolong rehabilitation; (3) previously ambulatory with the aim to restore a functional limb; (4) likely to engage with the significant physical therapy required for return to normal living; and (5) peak flow velocity of greater than 15 cm/s in the recipient artery. ⁸ ^, ²⁹ ^, ³⁹ ^, ⁴⁰ ^, ⁴¹ The following can be high risk for patients who may undergo reconstructive microsurgery: (1) patients who have had multiple angioplasties; (2) patients with severe peripheral artery disease; and (3) patients after kidney transplantation who are using immunesuppression. ⁸ ^, ²⁹ ^, ³⁹ Among these considerations, the most significant one will be perfusion of the recipient vessel. If any small vessel is seen with good pulsatile flow, it would be indicated for microsurgery. Thus, an absolute contraindication would be no flow to the foot without any sign of perfusion from any distal small vessels. This supermicrosurgery and free style reconstruction approach, however, will require a refined skill along with a paradigm shift for reconstruction. ¹⁵ ^, ²⁹ ^, ³⁹

18.5.1 Step-by-Step Approach for Reconstructive Microsurgery (Video)

Evaluate the general systemic condition of the patient.
Evaluate the vascular status and consider vascular intervention if needed to maximize flow to the foot. Identify potential vascular recipient site as well as flap donor site. Fig. 18‑5 shows that the anterior tibial artery is calcified and nonviable; thus, the choice to use the posterior tibial artery has to be made. Fig. 18‑6 shows that the major collateral vessel distally is the descending branch of the lateral circumflex femoral artery and one must avoid using the anterolateral thigh (ALT) as this would diminish the flow to the entire lower leg.
Debride the wound using angiosome concept and confirm the bleeding from the margins of the skin.
Identify the recipient vessels, visualize adequate pulse, and evaluate the relationship with the defect to determine the pedicle length.
The biggest challenge in reconstructive microsurgery for a diabetic foot is finding the recipient vessel. Even with an adequate flow to the foot, atherosclerosis of the artery may make anastomosis very difficult. If a named artery will be used as recipient, one must try to find a small segment spared from calcification. ¹⁰ End to side on the major artery, end to end on a branch form the major vessels, or a T-anastomosis can be considered to minimize the flow deprivation after anastomosis. Small perforators can be used as recipients as well. During debridement, pulsatile arteries are marked. If there is no pulsating small arteries in the lesion, search for an adequate small recipient artery can be extended to the adjacent healthy angiosome territory. Once a pulsatile perforator or a small artery is found, it is dissected and preserved. For the recipient veins, there is no preference over superficial or deep veins. Easily available veins during debridement are mostly used. ²⁹ ^, ³⁹
Elevation of flap with adequate pedicle length.
The flap for reconstruction of a diabetic foot should provide a well-vascularized tissue to control infection, adequate contour for footwear, durability, and solid anchorage to resist shearing forces. Controversy still remains as to which flap, whether muscle flaps with skin grafts, fasciocutaneous flaps, and recently added perforator flaps, offers the optimal solution to reconstruct the foot, especially the weight-bearing surface. But as long as the large defect is covered with any well-vascularized tissue, it will provide an independent and well-nourished vascular supply to eradicate infection, increase local oxygen tension, enhancing antibiotics activity, and neovascularization to the adjacent ischemic tissue. ⁴² ^, ⁴³ In our clinical experience, we are shifting toward using perforator flaps such as ALT perforator, gluteal artery perforator flap, and superficial circumflex iliac perforator flap as it provides a thin flap to minimize shearing, can take only the superficial fat to imitate the fibrous septa of the sole to adhere tightly, enhance neovascularization of the subdermal plexus with adjacent tissue, and provide adequate blood supply to fight infection. ¹⁰
Check the recipient vessel again prior to cutting the flap pedicle.
Cut the pedicle and anastomosis of the vessels. If the pulse looks look, consider elevating the systemic blood pressure.
An end-to-side anastomosis is highly recommended to preserve the flow to the feet. If vessels are calcified, one should look for a calcification spared segment or use a small branch from the major vessel as recipient. It is relatively rare to see branches from posterior tibial and dorsalis pedis arteries to be calcified and by using this branch one can easily anastomose to a supple and soft artery without diminishing distal flow. An alternative anastomosis may be the T-style anastomosis where bypassing artery segment with a branch to the flap is interanastomosed between the proximal and distal recipient artery. All efforts should be made to preserve the distal flow to the foot.
Insetting of the flap.

Fig. 18.5 CT angiography plays an important role in evaluating the overall flow of the leg. In addition, it provides information on potential recipient vessels. This examination shows that the anterior tibial artery is calcified and nonviable; thus, the choice to use the posterior tibial artery has to be made.

Fig. 18.6 CT angiography plays an important role in evaluating the overall flow of the leg. In addition, it also provides information in selecting potential flap donor sites. This examination shows that the major collateral vessel distally is the descending branch of the lateral circumflex femoral artery and one must avoid using the anterolateral thigh as this would diminish the flow to the entire lower leg.