A stress fracture (or hairline fracture) is a tiny break in the bone due to imbalance between load & resistance. These fractures are most often a result when muscles become fatigued, the fatigued muscle transfers the overload of stress to the bone causing a stress fracture. That happens often from overuse, such as overly stressing, repeatedly jumping or running long distances, repeated injury or overly stressing. in condition of osteoporosis or other that’s weakened the bone also may result trees fracture.
Sub-type of Stress fractures as follow
1) Fatigue fractures– it occurs due to the result of stresses increases on a normal bone.
2) Insufficiency fractures- it occurs due to the result of normal stresses on abnormal bone.