Shoulder Impingement Syndrome
Shoulder impingement syndrome is a common cause of pain and limited mobility in the shoulder. Pain can range from a dull, heavy discomfort deep in the joint, to an acute sharp one that spreads across the top of the shoulder and outside of the upper arm. Because it often produces profound loss of mobility, some doctors and physios often incorrectly diagnose impingement syndrome as a frozen shoulder, which is a very different and much rarer complaint. In this blog, I aim to explain where and how impingement syndrome happens, the tissues involved and how I try to help someone suffering from impingement syndrome
What is Impingement Syndrome
The NHS choices website defines impingement syndrome as “a very common cause of shoulder pain, where a tendon (band of tissue) inside your shoulder rubs or catches on nearby tissue and bone as you lift your arm”. Whilst simplistic this is a good starting place to better understand the condition.
Where does impingement occur?
Impingement syndrome occurs in the subacromial space. This space is more accurately known as a potential space. It is full of different tissues that under normal circumstances slide over one another without pain or dysfunction. The boundaries of this space are formed by the acromion and the coracoid process, two bony projections of the shoulder blade and a ligament that bridges between the two. These form the roof of the potential space. The floor is formed by the humerus, the bone of the upper arm.
What happens in shoulder impingement?
The shoulder is an example of a ball and socket joint. When raising the arm above the head the ball should spin on the spot to keep a space between the humerus and the acromion the same size. In impingement syndrome, this space is reduced and leads to tissues becoming compressed or pinched. This can be a result of the ball of the joint not spinning on the spot, arthritic bone growth occupying the space or because of bad posture.
What tissues get impinged:
Commonly impinged tissues are those that run in the subacromial space. These include the subacromial bursa, the supraspinatus tendon and the tendon of the long head of biceps muscle. The bursa’s role is to reduce friction between the tendons and the bony archway of the acromion whilst the two muscles named have key roles in moving the shoulder as well as stabilising it.
What can cause impingment syndrome?