A 64-year-old man with a history of type 2 diabetes mellitus comes to the physician with 3 weeks of left foot pain. He reports recent difficulty with ambulation that requires a cane. He has no fevers, chills, nausea, vomiting, malaise, or fatigue. The patient has a history of hypertension and poorly controlled diabetes mellitus complicated by mild renal disease and neuropathy. His current medications include insulin, lisinopril, metoprolol, and gabapentin.
His temperature is 37.1 C (98.8 F), blood pressure is 124/84 mm Hg, pulse is 90/min, and respirations are 18/min. Examination of the lower extremities shows decreased sensation to fine touch bilaterally extending to the knees. There is a 2x2 cm ulcerated lesion at the base of the left first metatarsal. The borders are clean without erythema. There is scant and foul-smelling purulent drainage at the base with poor granulation tissue and visualized bone.
An x-ray of the foot reveals cortical erosion with elevated periosteum.
Which of the following is the best next step in management of this patient?

Question

A 64-year-old man with a history of type 2 diabetes mellitus comes to the physician with 3 weeks of left foot pain.  He reports recent difficulty with ambulation that requires a cane.  He has no fevers, chills, nausea, vomiting, malaise, or fatigue.  The patient has a history of hypertension and poorly controlled diabetes mellitus complicated by mild renal disease and neuropathy.  His current medications include insulin, lisinopril, metoprolol, and gabapentin.
His temperature is 37.1 C (98.8 F), blood pressure is 124/84 mm Hg, pulse is 90/min, and respirations are 18/min.  Examination of the lower extremities shows decreased sensation to fine touch bilaterally extending to the knees.  There is a 2x2 cm ulcerated lesion at the base of the left first metatarsal.  The borders are clean without erythema.  There is scant and foul-smelling purulent drainage at the base with poor granulation tissue and visualized bone.
An x-ray of the foot reveals cortical erosion with elevated periosteum.
Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Poorly healing diabetic foot ulcers > 2 cm² are more likely to extend directly into bone (usually after 2 weeks) and cause osteomyelitis, which can be monomicrobial or polymicrobial. Hematogenous osteomyelitis is more common in children and tends to be monomicrobial. Acute osteomyelitis usually presents with gradual onset of dull pain with possible localized (eg, tenderness, warmth, erythema, and swelling) or systemic (eg, fever) findings. Laboratory studies may show elevated inflammatory markers (eg, ESR and CRP) that are more useful in determining response to therapy. ² Wound infections with erythema, warmth, tenderness, edema, and/or purulent secretions with visualized bone (as in this patient) indicate high probability of osteomyelitis and do not require other diagnostic studies. However, bone biopsy with culture is recommended to guide antimicrobial therapy unless blood cultures are positive for infection. Wound cultures are not recommended as they are often colonized with bacteria (Choice A). Plain radiographs may not show findings of acute osteomyelitis (eg, cortical erosion, periosteal elevation, or sclerosis) for 10-14 days. (Choices C and D) MRI is preferred in suspected osteomyelitis with normal radiographs but may sometimes overestimate the extent of infection. CT can be used if MRI cannot be obtained, and triple-phase bone scan may be ordered if neither CT nor MRI is available. However, triple-phase bone scan is not specific and may confuse osteomyelitis with other inflammatory bone conditions (eg, fracture or Charcot arthropathy). It may also be negative in patients with peripheral artery disease due to diminished blood flow. (Choice E) Treatment of osteomyelitis involves surgical debridement of necrotic material and antibiotics, which are usually started after appropriate cultures (bone biopsy and/or blood cultures) are obtained. Educational objective: Osteomyelitis should be suspected in patients presenting with an ulcer > 2 cm², duration > 2 weeks, visualized bone, and elevated ESR. Plain films may not show periosteal elevation and cortical erosion for 10-14 days. MRI is the most accurate imaging modality for diagnosis of osteomyelitis, especially in diabetics. However, bone biopsy is recommended in most situations to guide antimicrobial therapy. ² __________ References: Diagnostic accuracy of the physical examination and imaging tests for osteomyelitis underlying diabetic foot ulcers: meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/18611152) 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections. (http://www.ncbi.nlm.nih.gov/pubmed/22619242)

A 64-Year-Old Man with a History of Type 2 Diabetes