Shoulder impingement syndrome

Impingement of the shoulder occurs when one or more of the soft-tissue structures of the shoulder is compressed between bony structures or improperly rubs against them during movement. This is usually the result of some sort of shoulder instability or prior injury. To understand shoulder impingement, one has to understand the rotator cuff.

The rotator cuff consists of four muscles in the shoulder which serve to rotate the head of the humerus (upper arm bone) and stabilize it in the socket during shoulder movements. These four muscles (see picture below) consist of two external rotators (infraspinatus and teres minor), one internal rotator (subscapularis) and one abductor (supraspinatus). Collectively, they provide the primary support for the head of your humerus. If one or more of them are working incorrectly, impingement is one of the potential results. There are two main types of impingement: internal and external.

In internal impingement, the teres minor and infraspinatus are pulled into the posterior portion of the shoulder socket and rub against it, causing inflammation, pain, and often tearing of the muscles. This is seen primarily in throwing athletes such as baseball pitchers.

External impingement, on the other hand, is usually what the rest of us are likely to get. In external impingement, the suprapinatus (and sometimes the biceps tendon) is compressed between the acromion (part of the shoulder blade) and the head of the humerus, causing pain, inflammation, and often tearing. Individuals with external impingement of the shoulder will often notice pain and reduced mobility when attempting to lift the arm overhead; sometimes so intense that the movement is impossible.

Shoulder impingement rehab involves multiple steps, including identifying the source of the instability and strengthening the appropriate muscles. The exact mechanism behind impingement varies greatly between individuals as there are so many potential causes that unfortunately, I can’t offer specific advice as to how to begin rehabbing your shoulder. However, if you suspect you suffer from shoulder impingement, just email me or follow the link on my website to setup a free evaluation.

Problems of the rotator cuff are disturbingly common. Health statistics show 75% of those over the age of 50 suffer from some sort of rotator cuff pathology or another. I encourage you to catch the problem early and keep it from becoming worse.


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