The rotator cuff is a group of four tendons. These tendons connect the main muscles of the shoulder to the upper arm. The tendons and muscles stabilize the shoulder joint so you can raise and rotate your arm. Every time you raise your arm above your head, the upper tendon glides under the upper end of your shoulder blade.
Sometimes the shoulder blade is rough or abnormally shaped and rubs or scrapes the tendon. Over time, this can cause tiny tears and bleeding. When these tears heal, the scar tissue is weaker and less flexible than normal tendon, so the whole rotator cuff gets weaker. The weaker the tendon becomes, the greater its chances of tearing.
Without treatment, this cycle of inflammation, wear and tear, and limited use can lead to other shoulder problems, such as stiffness or frozen shoulder. Activities that require repeated overhead arm movements can lead to problems like bursitis and tendinitis.
Here are the things that can gradually lead to rotator cuff problems. They often occur together or overlap:
Irregularly shaped bones. These can affect how the rotator cuff moves. You may be born with these irregularities, or they may occur after some type of injury, such as a broken bone.
Aging. As you age, everyday activities and normal wear and tear lead to some changes in the rotator cuff, such as:
- General thinning, fraying, and tearing of the tendon.
- Reduced blood supply to the tendons.
Joint looseness and muscle imbalance in the shoulder. This can damage tissue.
Repetitive activities. Repeated activities, especially forceful overhead motions, are common in certain sports or occupations, including throwing a baseball, the overhead swing in tennis, swimming, lifting, or painting. These motions can eventually lead to tendons scraping against bone (impingement).
Overuse. This may occur with or be closely related to repetitive activities. Normal motions made often over a long period can stress or injure rotator cuff tissues. Athletes, including young people, may get tendinitis from overuse in throwing, swimming, and racquet sports.
It takes tremendous force to tear a healthy rotator cuff tendon. This may happen while you are playing sports or during an accident or a severe fall.
In older, less active adults, even simple movements such as lifting a suitcase can cause a tear .