The tendons attach to the bone and must be reattached after injury in order to give you back shoulder motion and strength. Some of the newer ways of repairing rotator cuff tears
involve drilling holes through the bone. Then the doctor threads the sutures through the tunnel to the other side. This gives the repair strength and the shoulder stability.
The sutures may not hold if the bone is soft or brittle from osteoporosis. In cases of bone problems, they can use special anchors that look like buttons to help hold the stitches in place.