A stress fracture of the neck of the femur (thigh bone) is an incomplete fracture or crack within the top of the thigh close to where it attaches to the pelvis.
In order to maintain a healthy bone structure, bone turnover is essential; bone turnover involves the removal of weakened, damaged areas of bone and the laying down of new bone at the same location.To do this, old bone is resorbed (removed) before it is replaced with new bone. If bone formation cannot keep up with bone resorption, areas of weakness can develop within the neck of the femur. These can develop into a stress fracture if the bone is continually loaded.
This can result from an imbalance between bone formation and bone resorption. Meaning, that when the neck of the femur is loaded or stressed, such as during weight-bearing exercise (running), it responds by increasing its bone turnover. This is necessary for it to live up to the demands on it.
Most stress fractures heal with rest and modification (Behrens et al., 2013); therefore, management includes reasonable loading during exercising and modification of lifestyle.
Behrens S.B. et al., 2013, Stress Fractures of the Pelvis and Legs in Athletes, Sports Health, 5(2); pp: 165-174