The rotator cuff consists of muscles and tendons around the shoulder that keep your arm in place. Each of the four muscles sits under the clavicle (collar bone) in front of the scapula (shoulder blade). They all have a corresponding tendon that links them to the upper arm bone (humerus), thus holding everything together. There are several different types of rotator cuff injuries, all of which can be relatively painful and interfere in everyday tasks. Here is a guide to understanding those injuries.
Causes
Most rotator cuff injuries are the result of repetitive motion—forcing frequent, strong upward rotation at the shoulder socket. The development of bone spurs (nodules of bone that generally form in the joints where bones meet) is not uncommon. This causes inflammation that irritates the tendons of the rotator cuff. Eventually, damage to the rotator cuff can lead to degeneration; the joint may become chronically weak or stiff. After the rotator cuff has been injured, future injuries become more likely—particularly since the chance of injuring the area increases as the musculoskeletal system begins to lose integrity with age. Some studies suggest a genealogical component to rotator cuff injuries, as well.
Risk Factors
Rotator cuff injuries are often an occupational hazard of particular jobs, namely athletes and tradesmen in construction jobs. Painters, builders (particularly because of movements like swinging a hammer or lifting and carrying heavy equipment), baseball players, and tennis players are more prone to rotator cuff injuries. Swimmers may also tend to rotator cuff impingement. Even semi truck drivers may have rotator cuff issues in the long run because of the strength and movement required to wrangle the wheel of such large vehicles under certain conditions. Different occupations and sports may be more likely to cause specific types of injuries than others; for example, rotator cuff tendinitis may be referred to as swimmer’s, pitcher’s, or tennis shoulder.
Types of Injuries
There are five main rotator cuff injuries, including:
- Rotator Cuff Tear: Tearing of a weakened tendon, resulting in pain and weakness.
- Rotator Cuff Tendinitis: Strain due to repetitive movement above the head (such as pitching a baseball). Symptoms include pain during movement (up, down, or behind) or when sleeping on the injured side; swelling or inflammation in the arm and anterior shoulder; stiffness; clicking sound during movement; and weakness.
- Rotator Cuff Impingement: Pinching of rotator cuff tendons between the acromion bone and the humerus. This term is often used synonymously with rotator cuff tendinitis, as symptoms and treatment are virtually identical.
- Subacromial Bursitis: Inflammation of the bursa, a thin cushion separating bone from other tissue at areas with a lot of friction. Symptoms include pain centralized at the outer shoulder, particularly when lifting the arm, that radiates toward but not past the elbow over time; inflammation; sensitivity and discomfort that is enhanced when laying on the affected side.
- Frozen Shoulder: Stiffness in the tissues surrounding the shoulder brought on by a lack of movement. Symptoms include pain and limited range of motion. Also called adhesive capsulitis, frozen shoulder is a potential complication of the rest required to heal rotator cuff injuries.
Diagnosis
Diagnosing rotator cuff injuries involves a physical exam, often with image testing. The physical exam will involve tactile investigation by your physician, accompanied by forced movement of the affected shoulder joint to see where pain and tenderness are centralized. The painful arc test involves lifting the arm straight out, from flat against the side to straight over the head. It’s often used to suggest the presence of impingement, although it’s not a definitive diagnostic tool.
Effective image testing may include ultrasounds, magnetic resonance imaging (MRIs), or computed tomography, among others. While a regular radiograph can be used to rule out other diagnoses, an arthrogram is a type of x-ray specific to the joints using injections of dye. The still image may show dye leaking out of the injection spot, suggesting a tear in the rotator cuff.
