Question of the Week

For April 28, 2020

A 45-year-old woman reports a 3-day history of redness and swelling on the dorsum of the left foot, associated with some discomfort on weight-bearing. She has a history of morbid obesity and hypothyroidism, as well as a 10-year history of insulin-treated type 2 diabetes complicated by retinopathy and neuropathy.

The patient is afebrile. There is erythema, warmth, and swelling over the dorsum of her left foot, along with pes planus that developed in the past year. She has full range of motion in her ankle and minimal pain with movement and weight-bearing. There is reduced vibratory sensation over the metatarsal heads and diminished ankle reflexes. The skin around her lower extremity is intact, with no ulcerated lesions.

Laboratory testing reveals a leukocyte count of 5300 per mm3 (reference range, 4500–11,000) and an erythrocyte sedimentation rate of 22 mm/hr (1–25).

Evaluation of the joint aspirate from the tibiotalar joint reveals a leukocyte count of 400 per mm3 and no crystals.

Which one of the following diagnoses is most likely in this case?

Osteomyelitis
Acute calcium pyrophosphate crystal arthritis (pseudogout)
Septic arthritis
Diabetic neuropathic arthropathy
Cellulitis