A 56-year-old man comes to the office due to a right foot ulcer that is not healing. He first noticed a small wound on the right sole 2 weeks ago but does not remember any trauma. The patient applied over-the-counter antibiotic cream, but the wound gradually enlarged and began draining foul-smelling material. He has had no fever or significant pain. The patient has a history of hypertension and type 2 diabetes mellitus. Temperature is 37.2 C (99 F), blood pressure is 140/80 mm Hg, and pulse is 86/min. Right foot examination shows a 2×3 cm plantar ulcer under the first metatarsal head. There is purulent exudate and the bone can be palpated with a sterile metal probe. Distal pulses are present, but lower-extremity sensation to light touch and pain is decreased. A recent hemoglobin A1c level is 8.9%. Which of the following is the best next step in management of this patient's foot ulcer?

Question

A 56-year-old man comes to the office due to a right foot ulcer that is not healing.  He first noticed a small wound on the right sole 2 weeks ago but does not remember any trauma.  The patient applied over-the-counter antibiotic cream, but the wound gradually enlarged and began draining foul-smelling material.  He has had no fever or significant pain.  The patient has a history of hypertension and type 2 diabetes mellitus.  Temperature is 37.2 C (99 F), blood pressure is 140/80 mm Hg, and pulse is 86/min.  Right foot examination shows a 2×3 cm plantar ulcer under the first metatarsal head.  There is purulent exudate and the bone can be palpated with a sterile metal probe.  Distal pulses are present, but lower-extremity sensation to light touch and pain is decreased.  A recent hemoglobin A1c level is 8.9%.  Which of the following is the best next step in management of this patient's foot ulcer?

Quizplus · Accepted Answer

Explanation: Patients with diabetes have multiple risk factors for the development of infected foot ulcers, including: peripheral neuropathy (eg, decreased lower extremity sensation, as in this patient): leading to impaired recognition of minor damage hyperglycemia (eg, elevated hemoglobin A1c, as in this patient): leading to impaired immunity peripheral arterial disease: further contributing to impaired healing once a wound is present Contiguous (nonhematogenous) extension of infection from the ulcer to underlying bone causes osteomyelitis. Because this complication may be asymptomatic, patients with diabetic foot ulcers should be assessed for extent of infection. As seen in this patient, the presence of a positive probe-to-bone test (palpating bone with a sterile, blunt wooden or metal tool), a large ulcer (eg, >2 cm²), or an ulcer lasting ≥1 week increase the likelihood of osteomyelitis. Fever, pain, an elevated erythrocyte sedimentation rate (ESR), and sinus tract drainage (eg, purulent drainage) may be present. ² The most specific diagnostic test for osteomyelitis is bone biopsy and culture. Bone biopsy, preferably performed before antibiotic initiation, allows for identification of the causative pathogens and tailoring of antibiotic therapy. Positive superficial wound cultures do not reliably predict the culprit organisms; even among patients with diabetes and foot ulcers who do not have osteomyelitis, wound base culture should be performed following debridement and curettage (ie, aseptically scraping the wound base with a blade or curette) rather than following a simple swab (which can be contaminated) (Choice E). (Choice A) Management of a foot ulcer complicated by osteomyelitis includes surgical debridement of necrotic material and prolonged (ie, multiple weeks) antimicrobial therapy. Amputation is the option of last resort and is used in instances of significant complications (eg, ischemia, necrosis) or when medical management fails. (Choice B) Although an elevated ESR (eg, >70 mm/hr) is suggestive of osteomyelitis in the appropriate clinical setting, it can be increased by any significant inflammatory process and therefore is nonspecific. In osteomyelitis, an ESR is helpful in following the response to antibiotic treatment; however, the diagnosis should ideally be established via tissue biopsy and the culprit organism identified via microbiologic examination. (Choice C) Although patients with diabetes are at increased risk for superficial fungal infections, invasive fungal infections are an uncommon cause of osteomyelitis, so fungal cultures are not a part of the standard evaluation. Routine blood cultures can be helpful in patients with osteomyelitis due to hematogenous spread (eg, infective endocarditis) but are less helpful in disease due to direct extension of local infection. Educational objective: Bacterial infection of a chronic diabetic foot ulcer may be minimally symptomatic and requires specific assessment. When the bone can be palpated with a probe, the risk of underlying osteomyelitis is greatly increased. Biopsy and culture of affected bone is critical to confirming the diagnosis and guiding management. References: Osteomyelitis in diabetic foot: a comprehensive overview. (http://www.ncbi.nlm.nih.gov/pubmed/28465790)

A 56-Year-Old Man Comes to the Office Due to a Right