Many people injure the rotator cuff and don’t realize it. Or they may have had a shoulder injury at one time but didn’t go see the doctor. Over time, the tissues either knit back together or filled in with scar tissue or fat. Pain, if present, went away.
But it’s also possible you just didn’t have any painful symptoms to alert you to the problem. This is more common in adults who experience degeneration of the rotator cuff as they get older. And it is also the case that some people simply have more pain, symptoms, and disability with a rotator cuff tear than others.
No one knows for sure why these differences exist. Experts suggest that age may play a role — and perhaps the strength of the other muscles around the shoulder. If the biceps and deltoid muscles are intact, they can accomodate for the loss of strength from the torn rotator cuff.
And then there is the size and shape of the tear itself. Large or massive tears that can’t be repaired (or repaired easily) present with more chronic symptoms. Left untreated, the body does what it can to heal itself. The affected individual does what he or she can do to adapt and the rest is history.