A 58-year-old man comes to the office due to an ulcer on the sole of the right foot. The patient noticed the wound 4 weeks ago. He has no history of trauma to the area. The ulcer has failed to heal despite wound care with moisture-retentive dressings and pressure offloading with orthotic devices. The patient has had no right foot pain, redness, swelling, fever, or chills. He has a 10-year history of diabetes mellitus complicated by diabetic neuropathy and nephropathy. He also has hypertension and hyperlipidemia. The patient does not use tobacco, alcohol, or illicit drugs. Vital signs are within normal limits. Physical examination shows a 3-cm ulcer under the first metatarsal head of the right foot; the wound has a clean base and no significant discharge. There is no surrounding erythema or areas of fluctuance or tenderness. Which of the following is the best next step in management of this patient's foot ulcer?
Patients with long-standing diabetes mellitus who have poor glycemic control are at high risk for diabetic foot ulcers. Risk is greatest in those with concomitant diabetic neuropathy, which reduces pain sensation and identification of ulcer, and peripheral vascular disease, which reduces immune recruitment and ulcer healing. Because diabetic foot ulcers are usually colonized by a wide range of organisms (eg, aerobic gram-positive cocci, enterococci, Pseudomonas, anaerobes), they are often complicated by adjacent soft tissue infection and/or underlying osteomyelitis.
Although these infections often occur simultaneously, osteomyelitis can arise without evidence of soft tissue infection due to neuropathy (diminished pain) and poor peripheral blood flow (diminished erythema, warmth, and purulence). Therefore, foot imaging (eg, x-ray, MRI) is generally recommended for all diabetic foot ulcers that are:
(Choice B) Although hyperbaric oxygen therapy is sometimes used in patients with poorly healing diabetic foot ulcers, evaluation for underlying osteomyelitis must occur prior to treatment because antibiotics and debridement might be required.
(Choice C) This patient with diabetes, hypertension, and hyperlipidemia is at high risk for peripheral vascular disease (PVD), which can be evaluated by angiography. However, initial testing for PVD usually consists of noninvasive studies (eg, ankle-brachial index testing). In addition, although this patient might eventually need angiography and possibly stents, evaluation for osteomyelitis is required first.
(Choice D) Although a deficiency of vitamin C or zinc can impair wound healing, supplementation with these vitamins should not be considered prior to ruling out underlying bone infection.
(Choice E) Although wound dressings are an important component of the treatment of diabetic ulcers, topical antibiotics should not be administered until osteomyelitis is ruled out. The presence of osteomyelitis necessitates systemic, not topical, antibiotics.
Educational objective:
A diabetic foot ulcer is a common complication of long-standing diabetes mellitus and is particularly common in patients with neuropathy and peripheral vascular disease. Deep, long-standing, or large ulcers require foot imaging (eg, x-ray, MRI) to assess for underlying osteomyelitis, even when no signs or symptoms of soft tissue infection are present. Ulcers associated with elevated erythrocyte sedimentation rate or C-reactive protein also require imaging.