Understanding shoulder impingement
Why it happens, how it's treated.
With three bones, two joints, and a web of tendons and muscles, your shoulder is a complicated structure. That makes it vulnerable to many problems.
One cause of shoulder pain is impingement. According to the American Academy of Orthopaedic Surgeons (AAOS), impingement happens when bones in the shoulder compress tendons or other tissues inside the joint.
Inside your shoulder
Shoulder impingement is one of several problems that can occur with the rotator cuff—a band of muscles and tendons that connects the shoulder blade (scapula) to the top of the upper arm bone (humerus).
The rotator cuff helps maintain stability of the shoulder joint. You use the rotator cuff muscles when you lift your arm and reach overhead. Usually, during that motion, the rotator cuff tendons—which are protected by a fluid-filled sac called a bursa—glide smoothly between the shoulder bones. But a number of problems can interfere with that normal gliding motion and cause shoulder impingement.
For example, according to the American Orthopaedic Society for Sports Medicine (AOSSM):
- Bone spurs can form, restricting the space between the top part of the shoulder blade and the upper arm bone.
- The tissue within this joint space can become inflamed and swollen due to conditions such as tendinitis or bursitis, which can happen because of overuse or repetitive overhead stress on the shoulder.
- Normal aging can lead to weakening and degeneration within the tendons.
According to the AOSSM, people with shoulder impingement commonly complain of shoulder pain that gets worse with overhead movement and can get severe enough to wake them up at night.
Symptoms of shoulder impingement shouldn't be ignored. Eventually, it can lead to a tear in the rotator cuff.
To diagnose a shoulder problem, your doctor will ask about your symptoms and check for tenderness. He or she will also check your arm strength and test your range of motion by moving your arm to various positions.
Tests may also be done. For example, x-rays can reveal bone spurs.
The goals of treatment for shoulder impingement are to reduce pain and get your normal shoulder movements back. Usually the first step is to temporarily stop doing the activities that cause pain. It's also important not to smoke, because smoking decreases blood flow to the rotator cuff.
According to the AOSSM, doctors also may recommend:
- Exercises to restore normal strength and flexibility. Your doctor or a certified athletic trainer or physical therapist can help you with an exercise program to strengthen your rotator cuff and other muscles involved in moving your shoulder blade. Exercise is the cornerstone of treatment for shoulder problems.
- Medication. Options include nonsteroidal anti-inflammatory medicine and injections of cortisone—a strong anti-inflammatory that is sometimes used to relieve pain.
- Surgery. This is not necessary for most cases of shoulder impingement. However, it may be helpful if other treatments haven't worked. Surgeons remove part of the bone or bursa to make more space for the rotator cuff. After you recover from surgery, you will need a program of rehabilitation exercises to restore your strength and range of motion.