Rotator cuff injuries can be difficult to diagnose. It is indeed true that many older adults with degenerative soft tissue changes have no symptoms. They are said to be asymptomatic.
Studies show that it is possible to have a full-thickness tear of the rotator cuff without any symptoms. Finding a clinical test that can accurately diagnose a rotator cuff tear has been a challenge. There are four different tendons that form the rotator cuff. There’s a different clinical test for each one.
But sometimes it’s impossible to separate out the supraspinatus from the infraspinatus (two of the commonly involved tendons). The surgeon may have to rely upon ultrasound or other more advanced imaging to make an accurate diagnosis. Many prefer arthroscopic exam because the repair can be done at the same time.
Ultrasound does have the advantage of being able to compare one side to the other without invasive surgery.