Foot Stress Fractures: Why do they occur?

These 3 photos should the fracture of a 4th metatarsal while the patient was not in an overuse situation. Questioning did not reveal any history of osteoporosis, although we talked about her VitD3 and Calcium intake. When I x rayed her foot, the fracture could be seen the best on an oblique view. Dr Susan Lewis, orthopedist at the Center For Sports Medicine in San Francisco told me that even though the bones on X-rays look strong, it takes a 40% loss in bone density before it is noticeable on X-ray. What is apparent on these X-rays is that the bone that broke has a probable benign bone tumor present, making the bone weaker. Any San Francisco Giant's baseball fan remembers when our All-Star Pitcher Dave Dravecky broken his arm pitching in a game only to find out that the the bone was weakened by a bone tumor. See the subtle changes in the 4th metatarsal which lean the walls of the bone making it prone for fracture. 

See the thinning of the walls of the fourth metatarsal.

This is an oblique view. An MRI has now been ordered.