Assessing The Use Of Ex-Fix For Offloading In Diabetic Limb Salvage

Dong Kim, DPM, Jeffrey McAlister, DPM, and Paul J. Kim, DPM

In lieu of the advancements in wound healing and innovations in surgical technique, limb salvage in the patient with diabetes remains a costly and complex endeavor. Some advocate immediate amputation for complex diabetic ulcers or gangrene.1 However, researchers have associated amputations in patients with diabetes with decreased life expectancy and an increased risk of contralateral amputation.2 The challenge with wound healing in patients with diabetes stems from the existence of comorbidities such as vasculopathy, neuropathy and propensity for infection.3

   With this in mind, a multidisciplinary team effort is warranted. This team should consist of: vascular surgeons re-establishing blood flow; podiatric and orthopedic surgeons performing debridements and ensuring skeletal stability; plastic surgeons for complex soft tissue coverage; and infectious disease specialists to stabilize the patient’s infection.4

   Despite the challenge, most superficial ulcers heal with definitive revascularization, local wound care including debridements, edema control and offloading. Final closure, however, becomes problematic when tendons, bones, joints and neurovascular structures are exposed. In such instances, viable reconstructive options for soft tissue coverage include local rotation flaps, pedicled muscle flaps and free flaps, according to the well documented reconstructive ladder.4 These flaps require strict postoperative management and offloading since known causes for flap failure may occur secondary to repetitive shear forces, pressure and premature ambulation.4,5

   Accordingly, let us take a closer look at the advantages and disadvantages of external fixation in the realm of free tissue transfer and their use in limb salvage.

What The Research Reveals About Flaps And Limb Salvage

Pedicle flaps require isolation of an identifiable, named neurovascular bundle supplying the donor tissue. They are generally more difficult to dissect and have higher complication rates than free flaps in the lower extremity.4 Pedicle flaps also have a limited coverage area due to their axis of rotation. Despite these shortcomings, there are some advantages to pedicle flaps. General anesthesia is not required, there is minimal functional deficit and the hospital stay is generally shorter.4,6

   However, free flaps (fasciocutaneous or muscle) can cover larger defects. The flaps are usually healthy muscle and work well for larger plantar wounds. The problem arises when the source vessels are calcified and difficult to anastomose. This often happens in patients with longstanding diabetes and end-stage renal patients. With free flaps, researchers have noted current limb salvage rates of 83.4 percent in a 28 month follow-up period.7 Authors have reported 77 percent survival rates at eight years following free flaps whereas survival rates at five years following amputation range between 22 and 38 percent.6,8

Addressing Potential Postoperative Concerns After Flap Reconstruction

Offloading is one of the most important factors to flap survival in the postoperative period.9 Motion along a joint, pressure and shear forces are undesirable and account for many flap failures.4 In addition, one needs to ensure elevation of the extremity for a period of time postoperatively to decrease swelling and encourage venous return.10 Authors have described many techniques, such as pillows and water mattresses, to offload the operative limb.11,12 However, these options do nothing to immobilize joints and are more suitable in simple wound care settings. Casting and external fixation are more appropriate methods to achieve immobilization and offloading during the postoperative phase.

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