Pathophysiology Although the spectrum of foot lesions varies in different regions of the world, the pathways to ulceration are probably identical in most patients. Diabetic foot lesions frequently result from two or more risk factors occurring together. In the majority of patients diabetic peripheral neuropathy plays a central role; up to 50% of type 2 diabetic patients have neuropathy and at-risk feet. Neuropathy leads to an insensitive and subsequently deformed foot, with possibly, an abnormal walking pattern.
In neuropathic patients minor trauma, caused for example by ill-fitting shoes, walking barefoot or an acute injury, can precipitate a chronic ulcer. Loss of sensation, foot deformities, and limited joint mobility can result in abnormal biomechanical loading of the foot. As a normal response callus is formed, but finally the skin breaks down, frequently preceded by subcutaneous hemorrhage. Whatever the primary cause, the patient continues walking on the insensitive foot, impairing subsequent healing (see figure 1).
Peripheral vascular disease, usually in conjunction with minor trauma, may result in a painful, purely ischemic foot ulcer. However, in patients with both neuropathy and ischemia (neuro-ischemic ulcer), symptoms may be absent despite severe peripheral ischemia. Micro-angiopathy should not be accepted as a primary cause of an ulcer. |
Fig 1. Illustration of ulcer due to repetitive stress |
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