The rotator cuff is located in the shoulder and is comprised of four muscles (Supraspinatus, Infraspinatus, Teres Minor, Subscapularis) connected by tendons. These muscles and tendons connect the head of the humerus (the upper arm bone) to the scapula (shoulder blade) socket and allow for rotation of the arm without dislocating the shoulder.
Types of Rotator Cuff Injuries
Rotator cuff injuries can be broken into three main categories:
- An acute tear is a tear in one or more of the tendons which results from some form of trauma. Some examples are lifting a heavy object or falling onto the shoulder, especially with an outstretched arm.
- A chronic tear can occur with repetitive motions. People more at risk for these injuries include athletes who swim or pitch for a baseball team, or construction employees like painters. Additionally, these conditions can be the result of an acute tear that did not heal properly, leaving the tendon weaker and more susceptible to damage.
- Tendinitis is a condition where the muscles and tendons become weaker, usually with age. As people get older, the blood supply to the tendons can diminish, making it harder to recover from injury. With tendonitis, the tendons associated with the rotator cuff are easily inflamed, causing pain or discomfort.
Signs of Injury
The signs of an acute rotator cuff tear include the feeling of tearing along with pain in the front and back, possibly radiating down the arm. There can be weakness in the affected arm due to the partial loss of muscle power. Additionally, since the integrity of the rotator cuff has been compromised, the sensation of the joint slipping out of place may be felt.
Signs of a chronic rotator cuff tear include a more gradual pain, especially at night making it difficult to sleep. There is also a gradual weakness making it harder to move the arm up and away from the side of the body or perform any lifting. A condition known as crepitus, or a crackling sound, is also an indicator of injury.
Indicators of tendinitis include a gradual onset of pain which can also be felt on the outside of the upper arm. The pain usually is greater when raising the arm from the side or turning it inward. Tendinitis is more common in older adults.
Diagnosis
Diagnosis starts with a physical exam in the doctor's office. The physician will perform a complete history, including the onset of pain and activities that aggravate or relieve it. The doctor will perform a physical exam to see if the pain is reproducible, and they will also check for other conditions such as arthritis or a pinched nerve.
The next diagnostic tool is an x-ray. This can check for injuries by looking at the positioning of the bones in relation to each other. Soft tissue cannot be seen on an x-ray, but an x-ray can detect other conditions that would cause pain—like a broken bone, a calcification that has formed on a tendon, or a bone spur.
Better diagnostic tools for rotator cuff injuries are Magnetic Resonance Imaging (MRI) and ultrasound. These tests can detect a tear in the tendon and show the location of the injury. They can also be used to detect degeneration in the muscles and tendons of the rotator cuff.
