What does a rotator cuff tear involve?

A rotator cuff tear specifically involves a tear in the muscles and tendons that stabilize the shoulder joint, rather than any of the other structures mentioned in the options. The rotator cuff comprises four main muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) that work together to allow for a wide range of shoulder movements and provide stability to the joint. When a tear occurs, it can cause pain, weakness, and limited range of motion in the shoulder, which is often experienced by athletes or individuals involved in overhead activities.

The other options describe injuries that pertain to different anatomical areas and conditions. For example, a tear in ligaments around the knee relates to knee injuries and does not involve the shoulder region. A fracture of the scapula would indicate a break in a bone, which is distinct from a soft tissue injury like a rotator cuff tear. Similarly, a muscle strain in the lower back pertains to a completely different area of the body and type of injury. Therefore, the choice that accurately describes a rotator cuff tear is one that identifies the involvement of the muscles and tendons around the upper arm.