In a rotator cuff disorder, tendons that make up the rotator cuff get squeezed and rub against bone. They become damaged and irritated. This causes bleeding and inflammation. The tendons can develop scar tissue, which is not as strong and flexible as normal tendon tissue. Over time, the tendons get weaker and less flexible. Eventually, they can tear.
Normal wear and tear and overuse cause most rotator cuff problems.
It takes great force to tear a healthy rotator cuff tendon. This can happen during sports, an accident, or a severe fall. But even a simple movement like lifting a suitcase can cause a rotator cuff tear in an older adult or someone whose shoulder is already damaged.