Age

The disease typically occurs around the age of 50.

Frequency

It is assumed that about 10% of the population suffer from pain-related movement restrictions of the shoulder.

Causes

Simplified, three components are involved in the development of an impingement syndrome. These are: Changes of one or the Kombinatinon of several components can be possible causes for the emergence of a Impingementsyndromes: While injuries at a younger age are primarily caused by acute trauma, ruptures of the rotator cuff at an older age (over 40 years) are often the result of chronic degeneration, i.e. wear and tear of the tendons. The supraspinatus tendon is most frequently affected.

People who work or act a lot with their arms above their head are often affected. This can be due to sporting activities (volleyball, handball, throwing sports and bodybuilding) or occupational (painters, mechanics). When the arm is held above the head, the subacromial space is narrowed.

Due to the impingement, the tendon of the supraspinatus muscle at the bottom of the bone is pressed, irritated and rubbed through over time, so that in the worst case, a rupture or partial tear of the tendon occurs. Before this, however, an inflammatory process of the tendon usually occurs, which leads to fluid retention and the smallest calcifications. If a rupture of the supraspinatus tendon is present, it can be treated differently.

Overweight of the muscle groups lifting the upper arm and the resulting rise of the humeral head
Incorrectly healed fractures of the humeral head
Thickening of the tendon at the rotator cuff due to overloading and/or training
Increase in volume of the tendon and bursa due to chronic inflammation
Calcium deposits in the tendon
Bony protrusions on the lower surface of the acromion
Arthrosis of the acromioclavicular joint (AC joint)
Unfavorable shape variants of acromion deviating from the norm, e.g. with the tip angled downwards
The humeral head
The acromion (formed from the acromion and ligamentum acromio-acromiale)
The rotator cuff with bursa subacromialis

A constriction between the head of the shoulder and the acromion can have various causes. In addition to primary and secondary arthrosis, an anatomically unfavorably shaped acromion can also lead to problems. This must then be redesigned by means of an operation so that the structures and soft tissues underneath can once again move smoothly.

In both cases, the subacromial space is constricted, which significantly limits the mobility of tendons and muscles. Calcification in the shoulder area can also lead to impingement syndrome. This so-called calcified shoulder mainly affects the tendons of muscles (mostly the supraspinatus tendon).

The cause of calcification has not yet been fully clarified. It is assumed that there is a reduced blood supply to the muscle groups that stabilize the muscles and their tendons, which can be triggered, for example, by a fall on the shoulder. Reactively, calcification occurs in the area of the tendons, which thicken and become inflamed when the irritation continues.

Arthrosis of the shoulder joint (omarthrosis) can be the cause of an impingement syndrome. In general, arthrosis is a mostly age-related change in the joint cartilage due to wear and tear. A distinction is also made between primary arthrosis and secondary arthrosis.

In the primary form, age-related wear and tear of the articular cartilage is the main cause, while in the secondary form, accidents or various diseases lead to pathological changes in the shoulder. In both cases, there is a reduction in the thickness of cartilage between the head of humerus and the glenoid cavity in the area of the shoulder joint, which significantly narrows the joint space between them. Due to the lack of cartilage mass, both bones rub against each other.

The result is increasing pain and significant restrictions in movement in all areas of the glenohumeral joint, with pain initially occurring during movement or when lying on the shoulder. As the disease progresses, these also occur when the patient is at rest. In the worst case, osteoarthritis in the shoulder joint can lead to frozen shoulder stiffness (“frozen shoulder”) or to a complete joint replacement.

Thickening of the bursa and tendon occurs in the case of inflammatory processes or constant incorrect or excessive strain. Bursae are fluid-filled structures that contribute to a reduction in friction and pressure load in places subject to particular mechanical stress. If an inflammation occurs, e.g. due to an impingement syndrome, they produce more fluid and swell.

As a result, muscles and tendons located in this area become trapped, leading to severe pain, overheating of the shoulder and restricted movement. Thickening of the tendons can be caused by a calcified shoulder, due to an impingement syndrome or also by an inflammation of the bursa. Due to the increase in size, they can no longer glide smoothly, resulting in pain and lack of mobility.

Sports injuries or accidents in the shoulder area can cause an impingement syndrome. Especially dynamic sports such as handball or volleyball, where an overhead movement has to be performed, represent a high risk. Tears of muscles or tendons, dislocation of the shoulder (shoulder dislocation) as well as falls on the shoulder joint occur particularly frequently. Accidents, such as a bicycle or car accident, can also lead to various diseases or fractures, which are accompanied by severe pain and significant movement restrictions in the shoulder and shoulder joint.