A fracture that develops over time?

Answer 1

A stress fracture can occur suddenly or slowly and (whether sudden or slow) it can worsen over time.

A stress fracture usually occurs on weight-bearing bones that are under "stress" of physical activity. For example, a tennis player might develop a stress fracture in the foot or ankle from strenuous activity during jumping, running, and rotation of the foot and ankle.

However, some people have weaker bones, often due to decreased calcium intake or that calcium leeches out of bones (for example, steroids can pull calcium from teeth and bones). Also, older people often have less hardened bones due to loss of calcium. In these situations, it does not require much force or stress on a bone to develop a stress fracture or hairline fracture (hairline means a very thin break, similar to looking at a single head hair on an X-ray film).