Periosteal Reaction

Description: The periosteum is a membrane several cell layers thick that covers almost all of every bone. About the only parts not covered by this membrane are the parts covered by cartilage. Besides covering the bone and sharing some of its blood supply with the bone, it also produces bone when it is stimulated appropriately. What does it take to make this happen? Practically anything that breaks, tears, stretches, inflames, or even touches the periosteum. So, when some anonymous process stimulates this reactive bone formation, eventually we see evidence of it on some imaging study.