In order to understand shoulder impingement syndrome, it is important to have a basic understanding of the shoulder joint. The shoulder joint consists of bones, tendons, cartilage and muscles that are all arranged around the joint to produce a variety of different movements.
The muscles of the shoulder joint form tendons are inserted in and around the joint, forming a structure called the rotator cuff. Between the bones of the shoulder joint and the muscles and tendons are small pockets of fluid that act as shock absorbers and lubricants. These are called bursa.
In shoulder impingement syndrome, the tendons of the rotator cuff and the underlying bursa are pushed against a part of the scapula bone (shoulder blade) called the acromion process. Constant contact between these structures causes inflammation and, subsequently, pain when the shoulder is moved.
The most common cause of shoulder impingement syndrome is overuse of the shoulder joint. It is particularly common in individuals whose occupations include construction and painting, as these professions require the shoulder joint to be under constant stress. Sporting activities such as swimming and tennis are also well-recognized causes.
Patients with shoulder impingement syndrome complain of pain from movement of the shoulder joint. In particular, attempts to reach behind the back or use the arm overhead can cause pain. On examination, the joint is swollen and tender with reduced range of movement. Often, patients do not experience any symptoms when the shoulder joint is being kept still. Typically, patients describe the pain as a sharp pain or ‘like a knife’ going through the shoulder.
In advanced cases of shoulder impingement syndrome, patients may develop a rupture of the biceps tendon.
Shoulder impingement syndrome is often diagnosed through clinical history and examination alone. Sometimes further investigation, such as an X-ray of the shoulder joint or MRI scan, can detect damage in a bit more detail. Ultrasound scans of the shoulder can also be useful.
Over-the-counter painkillers such as paracetamol and non-steroidal anti-inflammatory drugs are the first line of management. Patients are advised to rest the shoulder joint and avoid activities that can worsen the pain. Regular stretching can help but must be performed under a warm shower, as this can loosen up the muscles a little.
Steroid injections into the joint can help get rid of the inflammation and pain to some extent. These must be performed by trained healthcare professionals.
Physical therapy plays a very important role. Once the inflammation has subsided, physical therapists will advise patients on different exercises that they can do to strengthen the joint.
In cases where the above treatment options have failed, surgical treatment may need to be pursued.