Anatomic relationship of heel spur to surrounding soft tissues: greater variability than previously reported.

The stimulating factor for the development of heel spur (calcaneal exostosis) is controversial. In a sample of elderly cadaveric specimens, using radiographic, gross morphological, and histological investigation, we demonstrate that heel spurs are generally not found in the trajectory of traction from the plantar aponeurosis enthesis or plantar muscles. Rather, they are variably associated with soft tissues including loose connective tissue, fibrocartilage, muscle, and aponeurosis. Furthermore, the bony trabeculae of the spur are not aligned in the direction of soft tissue traction, but rather in the direction of stress on the calcaneus during walking and standing. These results substantiate the view that the heel spur may be a skeletal response to stress and may serve to protect the bone against the development of microfractures.