Foot Ulcer Pathophysiology and Risk Factors

Introduction to Foot Ulcers

• Foot ulcers are open sores or wounds on the foot that occur most commonly in people with diabetes, characterized by a break in the protective cutaneous envelope, typically at sites of trauma or pressure, and are associated with high morbidity, mortality, and significant financial costs 1, 2

Characteristics and Epidemiology

• Foot ulceration is a major complication of diabetes mellitus with a lifetime incidence rate of 19-34% and a yearly incidence rate of approximately 2% 1, 3
• After successful healing, recurrence rates are alarmingly high at 40% within one year and 65% within three years 1

Primary Pathophysiological Mechanisms

• Three main pathological mechanisms underlie foot ulcer development: neuropathy, vascular insufficiency, and secondary infection following trauma 2, 4
• Diabetic peripheral neuropathy plays a central role in ulcer development, with sensory neuropathy leading to loss of protective sensation, motor neuropathy contributing to foot deformities, and autonomic neuropathy reducing sweating and leading to dry skin prone to cracking 2
• Peripheral arterial disease (PAD) is present in up to 50% of patients with diabetic foot ulcers, acting as a significant risk factor for impaired wound healing and amputation 2

Types and Classification

• Foot ulcers can be classified by etiology as neuropathic, ischemic, or neuro-ischemic, with neuropathic ulcers occurring on the plantar surface or areas overlying bony deformities, ischemic ulcers more common on toe tips or lateral foot borders, and neuro-ischemic ulcers a combination of both mechanisms 5, 6

Risk Factors

• The International Working Group on the Diabetic Foot (IWGDF) identifies key risk factors, including loss of protective sensation, peripheral artery disease, foot deformities, history of previous foot ulceration or amputation, and end-stage renal disease 1, 3, 4, 6
• Abnormal biomechanical loading of the foot results from loss of sensation, foot deformities, and limited joint mobility, leading to high-pressure areas and callus formation 2, 6

Risk Stratification

• The IWGDF categorizes ulcer risk into four levels: very low risk, low risk, moderate risk, and high risk, based on the presence of loss of protective sensation, peripheral artery disease, foot deformities, and history of previous foot ulceration or amputation 2, 3

Incidence, Risk Stratification, and Recurrence of Diabetic Foot Ulcers

Incidence

• Lifetime risk: Between 19 % and 34 % of all individuals with diabetes will develop a foot ulcer at some point in their lives. 7
• Annual risk: Approximately 2 % of the diabetic population develops a new foot ulcer each year. This estimate is supported by multiple sources. [8][7]9
• Global prevalence of active ulcers: About 6.3 % of people with diabetes have an active foot ulcer worldwide, with regional rates ranging from 5.5 % in Asia, Europe, and Africa to 13 % in North America. 10

Risk Stratification (International Working Group on the Diabetic Foot – IWGDF)

• Category 0 (Very Low Risk): No loss of protective sensation and no peripheral artery disease; annual screening is sufficient. 7
• Category 1 (Low Risk): Either loss of protective sensation or peripheral artery disease; screening every 6–12 months. 7
• Category 2 (Moderate Risk): Loss of protective sensation plus peripheral artery disease or loss of protective sensation plus foot deformity; screening every 3–6 months. 7
• Category 3 (High Risk): Loss of protective sensation or peripheral artery disease plus a history of previous ulceration or amputation; screening every 1–3 months. 7

Ulcer Recurrence

• 1‑year recurrence: After successful healing, 40 % of patients experience a new ulcer within 12 months. [8][7]9
• 3‑year recurrence: The cumulative recurrence rate rises to 65 % within 3 years after healing. 7

Predictors of Ulceration

• Prior ulceration or amputation: A history of a previous foot ulcer or amputation is the single strongest predictor of future ulcer development. 7

Diabetes Mellitus as the Primary Risk Factor for Medial Foot Ulcers

Epidemiology

Pathophysiological Mechanisms

Risk Stratification

Clinical Assessment Recommendations

Management Guidance

All statements are supported by the cited references and reflect the current recommendations of the International Working Group on the Diabetic Foot (IWGDF).