The AC joint arthrosis
Shoulder joint arthrosis is the wear and tear of the acromioclavicular joint (AC joint) – also called ACG arthrosis, which covers the actual shoulder joint. Due to degenerative processes in the joint, acute, painful inflammatory conditions can occur time and again. The mobility of the shoulder is limited, and the area above the acromioclavicular joint can be swollen, reddened or warmed by pressure. The therapy is largely symptomatic. If pain is resistant to therapy, a space-creating operation can be performed, either open (skin incision) or arthroscopically.
Anatomy and cause
The joint is formed from the acromion – an extension of the shoulder blade and from the clavicle – the collarbone. The acromioclavicular joint is stabilized by many ligaments. The tendons of the rotator cuff run under the acromion, which are often irritated in case of arthrosis in the acromioclavicular joint.
The causes of joint wear are not always clear. Previous ligament injuries or severe mechanical stress on the acromioclavicular joint can promote the development of acromioclavicular arthrosis. The joint space becomes narrower and the cartilage mass decreases or even disappears completely.
Bony attachments can reduce the subacromial space (space above the humeral head and below the acromion). Tendons that run here can be irritated. This can lead to painful restrictions in movement. A narrowing of the subacromial space is also known as impingement syndrome.
Symptoms of acromioclavicular joint arthrosis
Typical symptoms of acromioclavicular joint arthrosis are the sensitivity to pressure over the joint and painful restrictions in movement when moving the arm. The ACG (acromioclavicular joint) covers the humeral head in the socket. When the arm is lifted, the bony head of the joint must rotate into the acromion, demanding a certain degree of mobility from it.
If the joint is arthrotically altered or is in an acute inflammatory state, the lifting of the arm in front of the body, but also the spreading sideways is painfully restricted. Reaching to the opposite side of the body also requires mobility in the ACG. A similar symptomatology is seen in shoulder arthrosis.
The shoulder girdle has to yield slightly to the movement, the degenerated joint surfaces rub against each other and pain occurs. The pain can occur after prolonged rest, during movement or even after exercise (e.g. after sports). The sensitivity to pressure over the joint often increases when carrying bags, but even more so when lying on your side. Many patients with acromioclavicular joint arthrosis cannot sleep on the affected shoulder and wake up at night due to pain.
