Cath Lab Digest

   Lower extremity limb preservation among patients with diabetes continuously challenges the foot and ankle surgeon. With a significant population afflicted by this disease, podiatric physicians often perform amputations, a complication related to diabetes.^1-4 The literature shows that pedal amputations occur in 60 percent of all nontraumatic lower extremity amputations with foot related disease as the most frequent cause for hospital admission.^4,5

   Transmetatarsal amputations, a common partial foot amputation, succeed with long-term effectiveness in limb salvage and function.^1-3,6-19 Compared to more proximal pedal amputations, this midfoot procedure proves to be the best option in respect to healing, function, patient satisfaction and long-term results.¹

   Current literature often refers to the introduction of transmetatarsal amputations by Bernard and Heute in 1855.²⁰ However, the initial application for trench foot has expanded. McKittrick later applied the procedure to other indications and introduced the adjunctive use of antibiotic therapy as a means toward facilitating a functional, salvaged limb.⁹ McKittrick emphasized antibiotic therapy as an integral treatment of transmetatarsal amputations for diabetic infections.⁹

   Indications for a transmetatarsal amputation include forefoot ailments due to infection, neuropathy, ischemia and chronic ulcerations.^{3,6,8-10,12,14,16,22,23} Often, a combination of the aforementioned indications complicates the presentation.¹ Due to a number of factors, conservative treatment often fails. In many instances, such as gangrene or chronic wounds, a transmetatarsal amputation remains the only viable option for pedal salvage.

   Ulcerations are not uncommon in patients with diabetes due to decreased neurovascularity and uncontrolled glucose. The continuous requirement for wound care is time-consuming, expensive and often futile due to the diminished vascularity clinicians often encounter. These chronic wounds may become worse and lead to osteomyelitis. When pathology is localized to the forefoot, removing necrotic osseous and soft tissue structures of the forefoot can provide a healing environment and a high probability of a functional limb.

Essential Keys To The Preoperative Evaluation

   The healing and success of the transmetatarsal amputation depends on many factors. Podiatric physicians must assess for common comorbidities, such as coronary artery disease, hypertension, renal disease and tobacco use, as they can affect and exacerbate the diminished health status of the diabetic population.^{2,6,10,12,13,16,21} Among patients with diabetes, decreased immmunocompromised health status and noncompliance issues contribute to the pathological pedal condition. Ensuring a multispecialty approach — with the aid of an internist, cardiologist and infectious disease specialist — can perioperatively optimize a patient’s medical status.

   During the initial evaluation, podiatrists should review the neurovascularity, dermatology and musculoskeletal status of the lower extremity for healing potential. There must be adequate, viable soft tissues available for coverage of the amputation site upon completion of the debridement. One should also check to see if there is decreased vascular status proximal to the forefoot.

   Indeed, sufficient vascularity is paramount for the healing of a transmetatarsal amputation.¹⁵ Angiogenesis is an important factor during the process of wound healing. Ischemia and severe distal atherosclerosis, a frequent finding in patients with diabetes, contribute to the failure of limb salvage.^{2,3,5,10,15,17,24-27}