I had an MRI, an X-ray, and an ultrasound of my shoulder. The doctor found two torn rotator cuff tendons. One was a partial-thickness tear and the other was full-thickness. what does this means exactly?

Damage to a tendon of the rotator cuff is usually called a rotator cuff tear. Minor fraying of the tendon but no other change in the tendon is counted as part of the "normal" aging process. But frayed pieces with a loss of tendon fibers is a partial-thickness tear.

Full-thickness tear means the tendon is severed all the way through. There is usually a gap seen on MRI or CT scan to show this. Sometimes a tendon will look normal on imaging studies. There are also times when a tear looks partial but is really full. The only way to know for sure is by doing arthroscopic or open surgery. At that time the diagnosis is confirmed with 100 percent accuracy.