Regional differences in strength at the plantar skin-fat interface

Mechanical factors are now widely recognized as important in the understanding of diabetic foot disease. Previous finite element modeling research suggested that the skin-fat interface might be the site for initial ulcer formation since peak first principal stresses at this location are dramatically increased by changes in material properties and boundary conditions. No study to date has investigated the effects of the disease process on the bonding between skin and underlying fat tissue on the plantar surface of the human foot. In total, 38 feet (70.9±2.2 years) have been studied. The plantar surface of the foot sample was divided into 18 areas. For each area the skin was peeled off the underlying fat tissue at a rate of I mm/sec by a materials testing machine. There was no difference between medial and lateral strips (p=0.603). The strength of the skin-fat interface was significantly higher in strips from the metatarsal head region and heel region than in mid-arch region of the foot. The strength of the skin-fat interface increased with the thickness of the skin at that site