Anatomy: Four muscles are part of the rotator cuff surrounding the shoulder joint, and controls, coordinates and assists movement of the shoulder: M supraspinatus (the upper shoulder blade muscle), M infraspinatus, M subscapularis and M teres minor. When the arm is moved away from the body and above the head (abducated) the supraspinatus muscle slips under the upper bone projection of the shoulder blade (acromion).

Cause: In case of repeated loads with the arm above the head (tennis, swimming) the upper shoulder blade muscle tendon (M supraspinatus) become inflamed swells and may become squeezed between the head of the upper arm (caput humeri) and the upper bone projection of the shoulder blade (acromion). Additionally this causes fraying and weakening of the tendon with risk of ruptures. It is not uncommon for tendinitis to be seen in conjunction with inflammation of the bursa (bursitis subacromialis).

Symptoms: Slowly insetting local tenderness after load, exterior and to the front of the shoulder. Sometimes radiating down the upper arm. The pain deteriorates when external pressure is applied to the supraspinatus muscle, on the front of the shoulder, when the muscle is activated (the arm is lifted to the side) and when the muscle is stretched (hand is brought to the loin). Due to the inflammation and wear and tear changes, calcification can occur in the shoulder muscle.

Acute treatment: Click here.

Examination: In light cases with only minimal tenderness medical examination is not necessarily required. In case of more pronounced pain or trouble lifting the arm away from the body and in case of lack of progress, a medical examination should be performed to ensure the correctness of the diagnosis and treatment. Ordinary clinical examination is often sufficient to make the diagnosis (article-1) (article-2). If there is uncertainty surrounding the diagnosis, it should be supplemented with an ultrasound scan, which is the most suitable examination for shoulder injuries (article).

Treatment: The treatment primarily involves relief from the pain inducing activities, stretching and rehabilitation of the muscles around the shoulder. If lack of progress in rehabilitation a medical treatment in the form of rheumatic medicine (NSAID) or injection of corticosteroid (usually in the bursa above the supraspinatus muscle) may be considered. Since the injection of corticosteroid is part of a long-term rehabilitation of a long-term injury, it is often necessary that the rehabilitation period stretches over several weeks to months, to reduce the risk of recurrences and ruptures. Naturally the tendon can not sustain maximum load after only a short rehabilitation period. If calcification is present in the shoulder muscle, an attempt may be made to extract this at the same time corticosteroid is injected around the calcification (article). The optimal effect at minimal risk can be accomplished by performing the injections guided by ultrasound. The wrong structures are hit in more than half the cases where the injection is done blindly (article). In lack of progress with rehabilitation and medical treatment a surgical treatment can be attempted.

Complications: If smooth progress is not achieved, it should be considered whether the diagnosis is correct or whether complications have arisen. Amongst others the following should be considered:

• Rupture of the upper shoulder blade muscle
• Rupture of the lower shoulder blade muscle
• Rupture of the deltoid muscle
• Rupture of the biceps muscle
• Ttendinitis of the biceps muscle
• Luxation of the joint between the shoulder blade and the collarbone
• Frozen shoulder
• Muscle infiltrations
• Sprained shoulder (distorsio art. humeroscapularis)
• Meniscus lesion in the shoulder (laesio labrum glenoidale)
• Impingement syndrome
• Nerve entrapment on the back of the shoulder blade