Shoulder Pain Part 2
Welcome back to part two of my series on shoulder pain. First, I want to do a quick review of shoulder anatomy (refer to the diagram of the right shoulder looking from the front). The upper arm bone (humerus) joins to the scapula at the glenoid and is held in place by two structures: (1) a rim of cartilage (glenoid labrum) that forms a shallow cup for the head of the humerus to sit in, and (2) the rotator cuff which is made up of four tendons that wrap around the head of the humerus.
As I described last week, in order for the shoulder to move in so many directions, it has to be inherently unstable. Since it is so unstable, two of the most common injuries are subluxations and dislocations. A subluxation is less severe than a dislocation. The ball does not completely come out of the cup. Subluxations are usually brief events with the head of the humerus returning spontaneously to its normal position. However, the shoulder can feel unstable afterward.
Dislocations result when the ball of the head of the humerus is forced out of its normal position in the glenoid cup and remains there. This usually happens when a person’s upper arm is hit from behind when the arm is raised to the side and the shoulder is cocked and ready to throw. Dislocations sometimes reduce spontaneously, but often require manipulation by a doctor to get the head of the humerus back in position.
Subluxations and dislocations can result in damage to various shoulder structures. The connective tissue capsule around the joint can be torn. One or more tendons in either the rotator cuff or attached to other muscles may be stretched or torn. The glenoid labrum may be torn as well. When these structures are disrupted, it makes the shoulder even more unstable and more likely to cause additional damage and repeated subluxations or dislocations.
Treatment for subluxations and dislocations usually involves rest, bracing, and strengthening the shoulder muscles with physical therapy. Surgery may also be required to repair a torn labrum or tendons.
Bursitis is another common cause of shoulder pain. Most of our joints are surrounded by fluid-filled sacs that pad the structures around the joint, particularly tendons. These sacs are called bursae (singular bursa). Bursae can become irritated, inflamed, and sometimes infected. Repetitive motion of the shoulder can irritate and inflame bursae resulting in an “overuse” injury. Weekend warriors frequently suffer from this malady. It’s not just the folks participating in throwing sports, but also those participating in other repetitive arm motions like painting their house, trimming trees, or shoveling snow.
Treatment of bursitis can be difficult. Standard treatment consists of rest and anti-inflammatory medication as well as icing. Doctors usually recommend non-steroidal medications (NSAIDs) such as ibuprofen (Advil® Motrin®) or naproxen (Aleve®). If those conservative treatments fail, we may recommend more potent steroids, either taken orally or injected into the bursa.
Impingement is the final condition I want to review. This term refers to structures in the shoulder coming into contact with one another resulting in pain. Impingement can be bone-on-bone or bone pinching or rubbing a tendon or bursa. While this happens more
commonly in people who have suffered shoulder injuries, it can also occur in an uninjured shoulder where anatomic structures are naturally close together.
Tendons that have been injured can swell, making them more likely to be pinched or rubbed with shoulder movements. The bones in the shoulder may also develop arthritis with bony overgrowth as a result of injury or natural aging. These overgrowths can also result in impingement.
Treatment of impingement varies based on the structures involved. Swollen, inflamed tendons or bursae are treated like bursitis. Occasionally, surgery is necessary to make more room for the structure(s) being rubbed or pinched. This can usually be accomplished through small incisions using a surgical tool called an arthroscope.
As always, prevention is the best medicine. If you participate in sports or work activities that involve a lot of shoulder motion, get involved in a fitness plan to keep your shoulder muscles strong, particularly your rotator cuff. Exercise programs are readily available on the Internet by searching for “shoulder exercises,” or “rotator cuff exercises.” You can find an excellent resource from the American Academy of Orthopedic Surgeons here: bit.ly/3xMPBz7.
– Dr. John Roberts is a retired member of the Franciscan Physician Network specializing in Family Medicine.