Evaluation of the diabetic foot
- David K McCulloch, MD
David K McCulloch, MD
- Clinical Professor of Medicine
- University of Washington
Foot problems are an important cause of morbidity in patients with diabetes mellitus. The lifetime risk of a foot ulcer for diabetic patients (type 1 or 2) may be as high as 25 percent . A potentially preventable initiating event, most often minor trauma that causes cutaneous injury, can often be identified. Foot amputations, many of which are preventable with early recognition and therapy, may be required . These observations illustrate the importance of frequent evaluation of the feet in patients with diabetes to identify those at risk for foot ulceration . Systematic screening examinations for neuropathic and vascular involvement of the lower extremities and careful inspection of feet may substantially reduce morbidity from foot problems.
Evaluation of the diabetic foot is provided here. A discussion of diabetes-related foot infections (cellulitis and osteomyelitis) and the management of diabetic foot ulcers are found elsewhere. (See "Clinical manifestations, diagnosis, and management of diabetic infections of the lower extremities" and "Management of diabetic foot ulcers".)
Several risk factors are predictive of ulcers and amputation. Early recognition and management of risk factors is important for reducing morbidity of foot ulceration. Most risk factors are readily identifiable from the history or physical examination. The most important are previous foot ulceration, neuropathy (loss of protective sensation), foot deformity, and vascular disease [1-4]. The significance of these risk factors was confirmed by the results of a community-based study of 1300 type 2 diabetic patients . The incidence of lower extremity amputation was 3.8 per 1000 patient-years. Predictors of amputation were foot ulceration (hazard ratio [HR] 5.6, 95% CI 1.2-25), ankle brachial index <0.9, elevated glycated hemoglobin (A1C), and neuropathy.
Neuropathy is present in over 80 percent of patients with foot ulcers; it promotes ulcer formation by decreasing pain sensation and perception of pressure, by causing muscle imbalance that can lead to anatomic deformities, and by impairing the microcirculation and the integrity of the skin. Once ulcers form, healing may be delayed or difficult to achieve, particularly if infection penetrates to deep tissues and bone and/or there is diminished local blood flow.
Risk classification — There are several risk classification systems designed to predict foot ulcer in patients with diabetes [6,7]. Risk categorization can be used to design preventive and monitoring strategies (table 1). One system, developed by the International Working Group on the Diabetic Foot, stratifies patients as follows :
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- RISK FACTORS
- Risk classification
- PHYSICAL EXAMINATION
- Physical signs of neuropathy
- Screening tests for peripheral neuropathy
- - Vibration sensation
- - Pressure sensation
- - Pain and temperature sense
- Physical signs of peripheral artery disease
- Foot ulceration
- - Wound evaluation
- - Signs of infection
- - Imaging
- - Wound classification
- SCREENING FOR RISK OF FOOT ULCERATION
- Preventive foot care
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS
- High risk for future ulcer