Introduction

About 27% of people > 55 yrs of age have peripheral arterial disease (PAD). Diabetics are 2–4 times more likely to have PAD. Around 15% develop PAD after 10 years of diabetes and 45% after 20 years. Diabetic foot accounts for the highest number of non-traumatic lower extremity amputations.

Definition

A neuroischaemic condition leading to soft tissue loss+/- infection over pressure-bearing areas.

Incidence

84% of patients with a 20-year history of diabetes have vascular disease and 75% die of vascular disease or its complications; primarily IHD and stroke. Gangrene occurs 50 times more commonly in diabetic males and 70 times more commonly in female diabetic patients as compared with non-diabetic patients.

Pathogenesis

Arterial occlusive disease in diabetics is a different pattern compared with atherosclerosis in non-diabetics. It mainly affects the distal popliteal segment, the tibial and metatarsal vessels with sparing of inflow and peroneal artery. Microscopically: thickening of the intima, increased thickness of the basement membrane, patchy distribution – diabetic microangiopathy.

Neuropathy: segmental demyelination of both sensory and motor nerves (defect in metabolism of Schwann cells) causing delayed nerve conduction. Distal nerves are affected more than proximal. Initial night cramps and paraesthesia progress to loss of vibratory sense and perception of light touch and pain and finally deep tendon reflexes are lost.

Motor dysfunction results in malfunction of the intrinsic muscles of the foot leading to distortion of foot architecture. It consists of extensor subluxation of the toes, plantar prominences of metatarsal heads and imbalance in action of flexors and extensors. The metatarsal arch then collapses. In its extreme form, the mid foot deteriorates leading to the so-called Charcot's foot.