Limb Salvage From a Podiatric Standpoint
Michael I. Gazes, DPM, MPH, FACFAOM, AACFAS
Peter A. Blume, DPM, FACFAS
I. Introduction
Salvaging the lower extremity for functional, efficient, and low energy ambulation is the ultimate goal after ischemia, trauma, or infection in the lower extremity. Surgical emergencies exist, including gas gangrene, septic joints, a necrotizing fasciitis, which can lead to dramatic tissue loss, complicating limb salvage efforts (Fig. 20.1). Peripheral neuropathy, leading to ulcerations, deep soft tissue foot infections, and osteomyelitis also require special and dedicated care to avoid loss of limb and/or life.
Peripheral neuropathy is the most common cause of foot ulcerations, with diabetes mellitus being the most common cause of neuropathy.1 Other causes also exist, including metabolic, toxins, viral and bacterial infections, genetics, ischemia, and inflammatory conditions. Patients with diabetes have a 15% lifelong incidence of developing foot ulcers, resulting in over 50% of nontraumatic lower limb amputations.2,3,4,5,6 Reduced vascular perfusion and decreased oxygen to the lower limb diminishes the body’s ability to heal suffocated wound sites, leading to prolonged exposure of open tissue to bacteria and increased likelihood of bone and soft tissue infection. Additionally, abnormal perfusion of blood to the foot can lead to weakening of bones. Combining weakened bones and neuropathy can lead to Charcot neuroarthropathy and major deformities at risk for wounds and infections, increasing the threat for major lower extremity amputation.7,8
II. Infection Control
A. Risk Factors Infection, particularly of an ulcer site, is a significant risk factor for lower extremity amputation.4,5 Infections can cause a delay in wound healing with deterioration of the surrounding tissue.9 Causes for lower extremity infections include vascular impairment, neuropathy, and decreased resistance to infection.9,10,11,12
B. Antibiotics Control of infection is typically via culture-guided antibiotics. Severe infections require intravenous antibiotics with prophylactic polymicrobial coverage prior to culture results including gram-positive and gram-negative anaerobes and aerobes.13 As
deep wound cultures become available, antibiotic coverage can be narrowed depending on growth. Mild soft tissue infections generally require 2 weeks of therapy.14 Deeper soft tissue infections may require up to 2 months of treatment.14 Osteomyelitis requires 6 weeks or longer of an antibiotic regimen in addition to surgical bone debridement.15 Prolonged ulcerations over osseous prominences should be evaluated for osteomyelitis. Improper footwear is the most common cause of neuropathic ulcerations, particularly when bony prominences or foot deformities exist.16
FIGURE 20.1: A, Gas gangrene visible with radiolucency by first metatarsophalangeal joint. B, Status post partial first ray resection with excisional debridement of all nonviable soft tissue and bone. C, Postoperative day 2.
C. Examinations A biomechanical examination and wound offloading removes abnormally high-pressure areas in a neuropathic patient. Techniques for offloading include accommodative inserts, total contact casting, braces, and the use of felt. Computerized gait analysis effectively assesses high pedal pressure locations, leading to increased orthotic customization. Studies found that total contact casting heals ulcerations faster than half shoes and removable casts.17 Patients given a removable cast were found to wear it for only 28% of their steps.18 Patients undergoing total contact casting have increased healing as demonstrated histologically with evidence of angiogenesis and formation of granular tissue as compared with patients treated with debridement alone.19 Contraindications to nonremovable casts include infection and/or ischemic wounds. Offloading via surgical procedures, such as exostectomies, tendon lengthenings or transfers, fusions, osteotomies, application of external fixation, and/or amputations may be required for adequate offloading of sites and ultimate wound reduction and prevention. Advanced wound healing products can also be attempted.
D. Osteomyelitis
1. Osteomyelitis, which on the foot typically occurs at ulcerative sites with bone prominences or at deep infection sites, is a highly destructive complication often necessitating long-term intravenous antibiotics, surgical debridement, or amputation. The average 5-year patient survival rate after amputation in the diabetic population is 39%.20 Surgically, eliminating the source of infection is the primary goal. The secondary goal involves salvaging the extremity for functional, efficient, and low energy ambulation. During resection, specimens should be obtained of both the infected site and clean margins for pathological and microbiological evaluation. Next, “dead space” must be managed to avoid further complications, including hematomas and creation of areas allowing further infectious reactions.
2. Sharp debridement of ulcerations off-loads sites by removing hyperkeratosis, necrotic tissue, foreign material, and infectious organisms.15,21 Sharp debridement should include the removal of all nonviable soft tissue and bone until healthy granular wound beds are obtained. Once infection has been eradicated, wounds can be closed or covered with primary wound closure, split thickness skin grafts, local flaps, or free flaps. If vascular perfusion to tissues are not adequate, clostridial collagenase is used for enzymatic debridement of the wound site.22 Hydrocolloid and hydrogel dressings lead to autolysis of necrotic tissues.
3. A variety of dressing options for ulcerations are available and are dependent upon wound etiology and patient characteristics. Treatment of peripheral edema is also beneficial.
4. Negative pressure wound therapy (NPWT) can be used to stimulate angiogenesis and the formation of granular tissue, decreasing overall healing time of wounds.23,24
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
