Diabetes, Foot Ulcer

Make the Diagnosis: Diabetes, Foot Ulcer

Prior Probability

Foot problems in patients with diabetes are common, but infections with osteomyelitis are extremely serious as they lead to an increase probability of amputation or death from complications. Among patients with diabetes with foot ulcers, about 15% have osteomyelitis.¹

Diabetic Population in Whom Osteomyelitis Should Be Considered

Patients with diabetes may have a peripheral neuropathy that decreases their ability to perceive pain, so all patients with diabetes are at risk for foot ulcers. Thus, frequent self-examination by patients and observation of their feet by their physicians is important. All patients with foot ulcers should be evaluated for osteomyelitis.

Assessing the Likelihood of Osteomyelitis

The assessment should focus on the physical examination findings and the erythrocyte sedimentation rate (Table 57-1). Ulcer area > 2cm² or the ability to probe to bone are the findings most suggestive of osteomyelitis. An erythrocyte sedimentation rate 70mm/h is similarly useful for identifying patients more likely to have osteomyelitis. These individual findings work as well, or better, than the clinical gestalt (LR+ 5.5, 95% CI 1.8-17) and an abnormal radiograph (LR+ 2.3, 95% CI 1.6-3.3). Inflammatory signs and swab culture are not useful as the likelihood ratio (LR) confidence intervals (CIs) cross 1.0 for both the LR+ and LR-. An abnormal magnetic resonance imaging (MRI) scan has an LR+ that is slightly better than a plain film radiograph (LR+ 3.8, 95% CI 2.5-5.8) but has greater utility when it is normal (LR- 0.14, 95% CI 0.08-0.26).

Reference Standard Tests

The reference standard for diagnosing osteomyelitis is a bone biopsy with culture of the specimen.

Reference

Original Article: Does This Patient With Diabetes Have Osteomyelitis of the Lower Extremity?

Clinical Scenarios

Case 1

A 52-year-old woman is referred from the emergency department with a diabetic foot ulcer. She has type 1 diabetes mellitus that was first diagnosed at age 12 years. Her condition is complicated by nephropathy, retinopathy, and peripheral vascular disease. She has recently noticed erythema, swelling, and pain over ...