Definition of Rotator cuff tendinitis:

Rotator cuff tendinitis is an inflammation (irritation and swelling) of the tendons of the shoulder.

Causes, incidence, and risk factors:

The shoulder joint is a ball and socket type joint where the top part of the arm bone (humerus) forms a joint with the shoulder blade (scapula). The rotator cuff holds the head of the humerus into the scapula.

Inflammation of the tendons of the shoulder muscles can occur in sports requiring the arm to be moved over the head repeatedly as in tennis, baseball (particularly pitching), swimming, and lifting weights over the head. Chronic inflammation or injury can cause the tendons of the rotator cuff to tear.

The risk factors are being over age 40 and participation in sports or exercise that involves repetitive arm motion over the head (such as baseball).