Definition
Bursitis subacromialis is the inflammation of a bursa in the shoulder joint, the bursa subacromialis. This bursa is located between the tendon of the supraspinatus muscle and the acromioclavicular joint (acromioclavicular joint or AC joint, consisting of the coracromial process (acromion) and the outer end of the collarbone (clavicle)). Bursa sacs practically serve as a “shifting layer”.
They reduce the mechanical stress on bones and muscles. A distinction is made between an acute and a chronic form of this inflammation. It is one of the most common shoulder diseases and is accompanied by severe pain.
Causes
As a rule, subacromial bursitis is caused by excessive or incorrect loading of the affected shoulder. Particularly at risk are persons who regularly have to perform a certain movement in which the arm must be raised above the head, for example tennis players or teachers writing on the blackboard. If such a strain exists over a long period of time, there are always minimal injuries to the bursa, which are not noticeable at first.
Over time, these so-called “micro-traumas” then lead to an inflammatory reaction in the bursa. Certain cells proliferate and produce more fluid and collagen. In addition, lime is often formed as a reaction to the constant mechanical irritation and stored in the tendons under the acromion.
When this calcium enters the bursa, it additionally promotes the inflammatory reaction. A special feature of the shoulder joint is that the subacromial bursa has little opportunity to expand. The deltoid muscle, the bony structures and the tendons limit the bursa very closely.
For this reason, subacromial bursitis is less likely to cause pronounced joint effusions with swelling compared to other bursitis, and movement is restricted more quickly. Other factors that can promote the development of bursitis in the shoulder are physical (excessive heat/cold, UV light, ionising radiation) or chemical (heavy metals, toxins, acids, alkalis) irritation, a derailment of the body’s enzyme balance or foreign bodies in the shoulder. It is less common for subacromial bursitis to occur as part of an underlying disease, for example malignant tumours, rheumatic diseases (especially rheumatoid arthritis) or metabolic diseases such as gout.
Symptoms
The main symptom of subacromial bursitis is severe pain. The pain of bursitis of the shoulder does not only exist during movements, but also at rest and in many patients even during the night. In the course of the disease, the pain is accompanied by a more or less pronounced restriction of movement of the shoulder joint, which can be accompanied by weakness in this very joint.
Occasionally, other symptoms typical of inflammation such as overheating or redness are added. In contrast, swelling in the shoulder area is rarely found in subacromial bursitis. Inflammations cause pain, at the beginning often only when the respective structure is strained or stressed.
The more pronounced the inflammation is, the sooner the pain finally shows itself at rest or even at night. Especially an inflammation of the bursa in the shoulder (bursitis subacromialis) can disturb the night’s rest, as different sleeping positions can lead to irritation of the affected bursa or simply put pressure on the affected shoulder. The clinical picture of “frozen shoulder” describes a chronic inflammation of the shoulder joint capsule (not the bursa subacromialis!
), which leads to a temporary stiffening of the shoulder joint through inflammatory adhesions. Patients between the ages of 40 and 60 are particularly frequently affected, with women more affected than men. In some cases, both shoulder joints may be affected at the same time, but the cause of this inflammatory disease has not yet been clarified.
The symptoms can last for months or even years and range from mere pain in the shoulder to more or less pronounced movement restrictions. Therapeutic measures can include conservatively prescribed painkillers, anti-inflammatory joint injections or surgical splitting of the shoulder joint capsule. Since subacromial bursitis is an inflammation of the bursa below the acromion in the immediate vicinity of the glenohumeral joint, it is often accompanied by a functional restriction in the joint. Because the affected bursa is located in the space between the shoulder joint and the acromion (part of the shoulder blade), and because this space becomes narrower, especially during arm movements such as lifting the arm between 80-120° to the side or forward, pain occurs during many everyday movements. In addition, movement restrictions and a significant reduction in strength in the shoulder can also become apparent.
