Summary
As a response to research investigating the intraosseous vascularization and the special biomechanics of the calcaneus, a new theory of calcaneal cyst development was generated (retrospective patient study, n=4). A disturbance in local blood circulation occurs, due to, i. e., microembolus, thrombosis, or hematoma, at the neutral triangle where the major vessels penetrate the bone and separate. Following the disturbance in local blood flow, damaged tissues are resorbed. Due to the special biomechanics of the area, resorption is followed not by osseous remodelling, but instead by cyst formation. The two processes are histologically identical, including the presence of neovascularization, cholesterol plaques, hemosiderin and osteoid-lined cyst walls. Because of its sclerosed external wall, the benign calcaneal cyst is stable with normal biomechanics; however, eccentric weight-loading can lead to fractures.