Tendons, muscles and bones comprise units. These units stabilize the pelvis and allow its motion. A strain occurs at the weakest part of a unit. There is no loss of strength.
Strength is diminished.
Severe strain requires surgical repair. Chronic strains are caused by overuse. Acute strains are caused by direct injury or overstress. Muscles and tendons of the trunk and hip. Pain when moving or stretching the leg or trunk.