Anatomical, histological, and histochemical studies were performed on normal and abnormal fat pads of the sole of cadaver feet. The fat pads were found to contain a significant nerve and blood supply separate from that to the surrounding musculature and skin. Pacinian corpuscles and free nerve endings within the fat were identified. Histological analysis indicated a meshwork of fibroelastic septae arranged in a closed-cell configuration. The mechanical consequences of this organization are discussed in the context of the weightbearing role of the fat pads of the feet. Alterations seen in dysvascular or senescent feet are consistent with the hypothesis that the septal anatomy of the fat pads is central to their cushioning function.

Contrary to previous reports, the peroneocalcaneal variant of the PQ muscle appears to insert in the retrotrochlear eminence of the calcaneus rather than the peroneal tubercle. The presence of the PQ muscle is associated with a prominent retrotrochlear eminence but not with an enlarged peroneal tubercle.

Light and electron microscopy was used for a histologic examination of normal heel fat pads and atrophic heel fat pads from patients with peripheral neuropathies. Histomorphometric analysis revealed an average 30% smaller mean cell area and 16% smaller mean cell diameters in the atrophic pads compared with the normal heel fat pads. Septal walls in the atrophic fat pads were often fragmented and approximately 75% wider than normal. Perineural fibrosis was also found in the atrophic heel fat pads. The Verhoeff elastic staining technique was used to determine the relative percentage of collagen to elastic tissue within the septae. No significant differences were noted between the normal and atrophic heels. The ultrastructure of the adipocytes from the normal and atrophic heel pads was similar to those found in abdominal subcutaneous fat. Lipid droplets of variable size and density thin the center of the adipocyte were surrounded by a thin border of cytoplasm. The interphase between adipocytes contained fine collagen and elastic fibers.