Chronic shoulder pain is often referred to as "Frozen shoulder" or "periarthritis", but what is really happening to your shoulder?
In most cases of chronic shoulder pain, disconfort comes with increasing elevation of the arm, with a maximum around 90° (arm horizontal).
The drawing below shows the shoulder joint. The arrows points at the acromion, a bony structure which is part of the shoulder blade. Very commonly, pain is caused by the acromion rubbing on the underlying supraspinatus tendon, which is part of the rotator cuff, a group of muscles that covers the humeral head from three sides. This phenomenon is called an impingement syndrome.
Usually, the first-line treatment is to make an injection of cortisone (a potent anti-inflammatory agent) into the space between the acromion and the tendon. It allievates the pain after a few days, and thereby confirms the diagnosis.
More recently, PRP (platelet-rich plasma)has been increasingly used instead of cortisone, because we believe it has more of a regenerative effect than cortisone.
In some patients unfortunately, chronic pain returns, and it becomes necessary to make radiographs and a magnetic resonance imaging (MRI) scan to establish wether or not the supraspinatus tendon is ruptured.Below, left: normal x-ray of the right shoulder: the acromion is flat, there is no impingement.Below, right: there is a bony spur at the tip of the acromion, which explains in this particular case why the pain has returned after the effect of the cortisone has worn off.
The MRI scan below shows the impingement zone. The suprapinatus tendon is completely torn, resulting in a gap in the rotator cuff. This is the result of several years of impingement, which is painless at first.
Some of these ruptures can also be caused by an accident, such as a fall on the shoulder or on the outstretched arm.