Figure. Image of the left foot.
A 64-year-old woman presents to the emergency department with complaints of an ulceration along the fifth metatarsophalangeal joint that has developed within the past week. She has a history of uncontrolled type 2 diabetes, coronary artery disease, and peripheral neuropathy. She is afebrile and has a white blood cell count of 12 x 109/L. Blood cultures obtained at hospital admission show a Staphylococcus aureus bacteremia. Two years ago, the patients underwent an amputation through the interphalangeal joint of the first toe. Radiographs of the foot show no evidence of osteomyelitis. Physical examination reveals a 2 cm x 3 cm ulceration along the fifth metatarsal with surrounding erythema that extends to the dorsum of the foot (Figure). She has 2+ palpable dorsal pedalis and posterior tibial pulses. Magnetic resonance imaging (MRI) of the left foot does not display identifiable abscess, fluid collection, or osteomyelitis.
Submit your diagnosis to see full explanation.
The loss of protective sensation in patients with diabetes and peripheral neuropathy can result in ulcerations of the foot. The most common locations for foot ulcers involve bony prominences such as the base of the fifth metatarsophalangeal joint, the top of the toes, and side of the foot. Prior amputation of the foot digits can change the mechanics of the foot during gait and increases the risk of ulceration in other locations.1
When evaluating foot ulcers, peripheral arterial disease (PAD) should be ruled out first as ulcers are unlikely to heal without adequate perfusion. PAD has a 20-fold higher prevalence in patients with diabetes than those without and should be ruled out by checking distal pulses first.2 A monofilament test confirms the diagnosis of peripheral neuropathy; a positive test is when the monofilament can be pressed against the foot with enough pressure to bend the filament without the patient experiencing symptoms.
Debridement is considered an essential part of the treatment of neuropathic foot ulcers. The goal of debridement is to remove non-viable necrotic tissue that inhibits wound healing. Bacteria inhibits wound healing by slowing epithelialization and collagen deposition; therefore, debridement removes bacteria and converts a necrotic ulcer to a viable healing environment.3
This patient underwent surgical debridement of her ulcer to remove all devitalized tissue until viable bleeding tissue was present. MRI did not show osteomyelitis, so it was not necessary to remove any bone during debridement.3,4
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Armstrong DG, Boulton AJM, Bus SA. Diabetic foot ulcers and their recurrence. New Engl J Med. 2017;376:2367-2375.
2. Weitz JI, Byrne J, Clagett GP, et al. Diagnosis and treatment of chronic arterial insufficiency of the lower extremities: a critical review. Circulation. 1996;94(11):3026-3049.
3. Gordon KA, Lebrun EA, Tomic-Canic M, Kirsner RS. The role of surgical debridement in healing of diabetic foot ulcers. Skinmed. 2012;10(1):24-26.
4. Yammine K, Assi C. Conservative surgical options for the treatment of forefoot diabetic ulcers and osteomyelitis. JBJS Rev. 2020;8(6):e0162.