A rotator cuff tear is a tear in one or more of the tendons of the muscles that surround the shoulder joint and help with arm movement.
Shoulder pain (often worse at night and when reaching overhead), weakness lifting the arm, clicking, and difficulty with everyday tasks like dressing or washing hair.
Imaging shows which tendon is torn, the size of the tear, whether it is partial or full thickness, and how much retraction has occurred.
Ultrasound and MRI are both used; MR arthrography may help characterise complex or recurrent tears.
Treatment ranges from physiotherapy and pain control for small or partial tears to surgical repair for large, symptomatic full-thickness tears, especially in younger or active patients.
This entry explains the finding. The next step is having a radiologist interpret your specific scan, not a general definition.