Impingement is a term that is often used. It derives from the English language and means something like ‘pinching’. Tendons run between the humeral head and the acromion, which are very important for the mobility and function of the shoulder. In addition, a bursa (bursa subacromialis) is found there, which acts as a sliding cushion between the bones and tendons. The genetic predispositions (anatomy) of the acromion and humerus, in other words, the composition and structure, are significant factors in determining whether impingement syndrome is promoted. For example, there are bony tubercles (tubercula majus and minus) on the humerus to which the tendons of the rotator cuff attach.
These can collide with the acromion during specific movements and cause pinching of the tendons and bursa. This space can become too narrow for various reasons (ossification, tendon condition, etc.) and interfere with the effortless gliding of the structures. As a result of this constriction, the soft tissues become pinched and chronically irritated due to movement, which can cause inflammation of the bursa (bursitis), and in the worst cases, even tendon ruptures. If you put on thick ski socks, for example, and slip into tight shoes, you can get blisters or irritation after a specific time. It is similar to the bursa when it is chronically pinched.