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A 66-year-old Hispanic man presented to the hospital with complaint of left foot pain. The patient related a history of living at a rehabilitation facility following a transmetatarsal amputation at a hospital one month prior.
The patient’s medical history included diabetes, hypertension, peripheral arterial disease and neuropathy. Upon initial encounter, it was evident that the patient underwent an open transmetatarsal amputation without secondary closure. Over time, the patient experienced increasing pain in his foot with associated redness. Physical examination revealed absent pedal pulses along with retraction of soft tissue about the amputation site with one centimeter of exposed metatarsals (Figures A-C). The marrow of the bones were necrotic in addition to the surrounding soft tissues with mummified changes. Ascending cellulitis was present. Radiographs of the foot were taken, but no free air was noted.
What’s your diagnosis?
A. Wet gangrene.
B. Burn.
C. Dry gangrene.
D. Neuropathic ulcer.
CASE DISCUSSION
Preoperatively, the patient was antibiosed on vancomycin. He underwent lower extremity arterial doppler, which demonstrated hemodynamically significant arterial occlusive disease located in the aortoiliac and superficial femoral and the infrapopliteal distributions of the affected left side. Ankle brachial indices were unreliable secondary vessel calcification resulting in falsely elevated pressures. Vascular service was consulted. Surgery was planned for a more proximal midfoot amputation. Initial surgery consisted of removal of all gangrenous tissue and bone (Figure D).
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After a few days and demarcation of necrotic tissue, the patient underwent secondary delayed primary closure with minimal bleeding encountered (Figures E-G). Following the primary surgery, the antibiotic was appropriately changed to Linezolid upon cultures showing VRE, with the cellulitis and infection resolving. Unfortunately, the patient suffered two setbacks of unexplained gastrointestinal bleeding and no vascular intervention was undertaken during this hospitalization. Once stabilized, the patient was released. However, outpatient follow-up by the rehabilitation facility on the patient’s behalf was not executed, and the patient was later found to have undergone a below-the-knee amputation at another facility and subsequently readmitted to our facility with poor healing amputation site and infection.
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Figures A – C: Prior transmetatarsal amputation with exposed metatarsals 1-4 with soft tissue retraction. Note soft tissue involvement proximally dorsally (A) and plantarly (B). Stable dry gangrene of the soft tissue and bone with mummification. |
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Gangrene is an unfortunate final pathologic manifestation of ischemia. This process yielding from dysvascularity can be setup by various disease states such as diabetes, collagen vascular diseases, isolated vascular disease and others. The recognition of the presence of gangrene and its potential is important for early treatment and intervention.
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Figure D: Site of demarcation after initial debridement. |
Gangrene can be a slow process regarding presentation or of a more acute onset and can present as dry, wet or gas gangrene or combination. Dry gangrene tends to be more stable and presents with necrotic tissue with a firm eschar. Gangrene is not limited to distal aspects of digits; it can appear in isolated areas of the leg, heel or part of the foot. At times, the eschar may deteriorate or regress and become soft or begin extending peripherally from its formerly stable borders, thereby converting to wet gangrene. Areas of extending borders may be stabilized using Betadine to dry up the area. Wet gangrene presents with a softer eschar with a more progressive extension of the peripheral borders over a shorter period of time. Great tissue loss and destruction is also seen with spreading wet gangrene with active drainage not uncommon. Infection can also manifest itself with cellulitis and, as in wet gas gangrene, with the presence of aerobic and anaerobic bacteria proliferating, causing a fetid malodor and intense pain.
Regarding vascularity, the presence of pedal pulses does not necessarily correlate with adequate distal perfusion of the forefoot and digits nor does the absence of palpable pulses correlate to loss of limb. With any evidence of physical examination alluding impaired vascularity including ischemic pain, arterial studies should be ordered as well as a vascular consult to determine degree of intervention. Both invasive and noninvasive vascular tests are resources and include arterial dopplers with waveforms, magnetic resonance, computed tomography, angiograms or arteriograms, among a few. In those with peripheral arterial disease with small vessel calcifications, falsely elevated toe pressures may result secondary to calcification of the vessel walls; thus, doppler tests are not 100% reliable in determination of level of amputation or potential for healing.
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Figures E – G: Secondary debridement with disarticulation of the metatarsal with decent bleeding and without signs of compromised osseous integrity to the cuneiforms and cuboids. Final delayed primary closure with drain placement. |
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Treatment varies on individual presentation and ranges from self-demarcation with or without autoamputation to stabilization of the gangrene with use of Betadine or use of Xenaderm cream applied along the periphery of gangrenous tissue to surgical intervention. Surgery can include removal of gangrenous eschar to removal of affected area in toto. Surgical intervention must take into account reestablishment of vascular flow to the affected portion. Depending on the state of the patient’s overall health, revascularization may have to be on hold until the patient’s health is optimal. In the case of small vessel disease, inflow to the smaller calicified vessels are not grossly reestablished as the larger vessels; yet, it does not constitute the revascularization as ill fated.
Patris Toney, DPM, MPH, is an Attending Staff Physician at Mount Sinai Hospital in Chicago, Ill. and Past Fellow at the Center for Lower Extremity Ambulatory Research / National Center for Limb Preservation.