Analysis of the heel pad fat in rheumatoid arthritis.

The heel fat pad is organized, both in structure and in composition, to bear the stresses and strains of normal activities and to permit pain-free weightbearing. The fatty acid composition of heel pads in 11 patients with rheumatoid arthritis, a disease process frequently associated with heel fat pad atrophy, was analyzed using gas-liquid chromatography and was compared with that of patients without systemic disease. The heels of patients with rheumatoid arthritis demonstrated a significant change in the composition of saturated fatty acids when compared with heels of nonrheumatoid patients. This composition reflects an increased fat viscosity, which decreases the ability of the heel to absorb and dissipate the energy generated during ambulation. This factor could cause degeneration of the heel septal system, with resulting fat pad atrophy.