Evaluation of the Diabetic Foot

Reference: Brodsky, James, Instructional Course Lectures, Vol 48, Chapter 36, 1999

Main Message
Diabetic foot problems are common. Must think about the connection between neuropathy and vasculopathy.

Points of Interest

– 5.9% of Americans have it – 1/3 are underdiagnosed.

Pathophysiology: two major factors (Neuropathy, Vasculopathy)
1. Neuroapathy – sensory, autonomic, motor
– most diabetic problems begin as a result of local trauma and tissue damage caused by the loss of or diminution of protective sensation.
– repetitive trauma at subfailure levels can, over time, cumulate to produce tissue necrosis
– sensory neuropathy is most important – tested with Semmes-Weinstein
– autonomic neuropathy cases abnormalities of skin temperature regulation, and sweating – leads to dry, chapped, fissured skin through which bacteria can get in. Hyperemia results from loss of autoregulation of small vessels – postulated to weaken the tissues as well.
– motor neuropathy – contributes to deformity creation by way of contractures. Contractures results in claw toe deformity from intrinsic scarring. This MTP extension, with IP flexion causes the MT heads to bear more weight and increases the risk of breakdown.

2. Peripheral Vascular Disease – macrovascular disease
– unlike the normal “atherosclerotic” they get distal lesions below the knee. The lumenal narrowing is ragged and widespread unlike the focal atherosclerotic patches. The calcification lies in the media, rather than in the intimal layer (nondiabetics).
– microvascular disease has been demonstrated, but these have not been correlated to ulcer formation. Thus, the cause of diabetic ulcerations cannot scientifically be ascribed to microvascular disease. Neuropathy continues to be a sufficient and pathophysiologically accurate explanation for most lesions.
– macrovascular disease, however causes ISCHEMIC PAIN. Watch out for this!
– pain can also come from a Charcot joint.

3. Deformity
– most commonly, the claw toe – MTP extension, IP flexion deformity
– also, look for prominences from Charcot joints collapsing, equinus deformity, hindfoot varus or valgus.
– look for the primary and the resultant deformities – must treat the primary deformity (eg- hindfoot varus causing ulcer over base of 5th MT – must treat the hindfoot varus!)
– It is accurate to say that all neuropathic ulceration requires the combination of 2 factors – insensitivity (caused by neuroapathy) and pressure (caused by deformity)

4. Immune Abnormalities
5. Gait Abnormalities

6. Systemic Abnormalities
– Glucose control, nutritional status

The article then discusses the “Depth/Ischemia” classification of diabetic foot ulcers, which gives them a 0-3 grade for depth and a A-D grade to ischemia/vascular status of the limb.

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