Shoulder Impingement Syndrome (Impingement Syndrome) - Medical experts provide information on treatment of the shoulder joint

Impingement is a mechanical compression syndrome in the so-called subacromial space—that is, the area between the head of the humerus and the acromion. In this anatomically narrow space, the delicate tendons run beneath the acromion—primarily the tendon of the supraspinatus muscle, which is part of the rotator cuff—as well as the protective bursa, the subacromial bursa.

If there is an increase in volume due to swelling, inflammatory processes, or bony changes, these structures are subjected to mechanical stress every time the arm is raised. The repeated friction leads to microtears, increasing inflammation, and, in the long term, degenerative changes in the tendon.

A distinction is made between primary and secondary impingement syndrome.

Primary shoulder impingement syndrome is usually caused by a structural factor, often related to bone. Typical causes include a prominent bone spur, osteoarthritic changes, or an unfavorable shape of the acromion, which further reduces the available space. 

In contrast, secondary impingement syndrome arises from functional disorders, such as muscular imbalances, instability of the shoulder joint, poor posture, or excessive strain. Changes in the spine can also indirectly affect the structures of the shoulder and lead to abnormal joint mechanics.

Internationally, the condition is referred to by various terms, including “impingement syndrome,” “impingement syndrome of the shoulder,” “rotator cuff impingement,” or “impingement syndrome.” In German-speaking countries, the term “Impingementsyndrom” is also commonly used.

As the syndrome progresses, the vicious cycle of swelling, irritation, and mechanical constriction intensifies until the soft tissues become permanently pinched.

The development of shoulder impingement syndrome is multifactorial in most cases. Anatomical peculiarities of the acromion, age-related changes in the shoulder joint, chronic overuse at work or during sports, and insufficiently trained or imbalanced muscles of the shoulder girdle contribute significantly to the development of the condition.

Pre-existing damage to the rotator cuff also increases the risk, as a weakened or thickened tendon further reduces the available space. As the condition progresses, the bursa often thickens as well, causing the subacromial space to narrow further and the symptoms to worsen. Ultimately, the affected soft tissues can no longer glide freely; instead, they are mechanically irritated with every movement of the arm, and in some cases, they become actually pinched.

The primary symptom is activity-related shoulder pain. Typical symptoms include:

• Shoulder pain during movement
• Pain in the shoulder when abducting the arm laterally
• Pain when raising the arm
• Nighttime pain, especially when lying on the affected side
• Loss of strength in the arm
• Limited range of motion in the affected shoulder
• Pain when moving the upper arm

Another characteristic feature is the so-called “painful arc”: The pain occurs particularly when the patient raises their arms to shoulder height, usually between 60 and 120 degrees of abduction. Activities performed overhead, repeated lateral lifting, or targeted shoulder movements are perceived as extremely painful by those affected.

The diagnostic process is carried out step by step and begins with a detailed medical history and a structured physical examination. During this process, the physician assesses range of motion, muscle strength, pain localization, and typical provocation maneuvers. In many cases, the clinical picture can already be determined with a high degree of certainty.

Imaging techniques are used to confirm the diagnosis. X-rays primarily reveal bony changes and the shape of the acromion. Ultrasound examination allows for a dynamic assessment of the tendons and changes in the bursa. Magnetic resonance imaging (MRI) provides a detailed view of the rotator cuff, any possible tears, and the involvement or damage to the supraspinatus muscle and other intra-articular structures of the shoulder joint.

By RSatUSZ - Own work, CC BY-SA 3.0, Link

Conservative treatment is always the first step in therapy. Treatment typically begins with targeted medication to relieve pain and reduce inflammation in order to alleviate acute irritation of the affected structures. The goal is to relieve pain, control inflammation, and restore normal function to the shoulder joint. Anti-inflammatory medications are generally used for this purpose; in cases of severe symptoms, local cortisone injections may also be administered as a supplement.

A central component is physical therapy. Through targeted strengthening and coordination of the shoulder girdle muscles, joint mobility can be improved and pressure on the irritated structures reduced. In addition, temporary rest, adjustments to sports activities, and, in select cases, shock wave therapy may be beneficial. This form of conservative treatment leads to significant and lasting improvement in many patients, especially when accompanying bursitis is consistently treated as well. 

If symptoms persist despite consistent treatment or if there is marked structural narrowing, surgical treatment is indicated. Today, surgery is performed almost exclusively as a minimally invasive arthroscopic procedure known as acromioplasty.

A camera and special instruments are inserted into the joint through several small incisions. First, the shoulder joint is examined; then, the inflamed bursa (bursitis) is removed, and excess bone is shaved off the acromion. This results in targeted subacromial decompression, which expands the space and permanently relieves pressure on the sensitive tendon structures.

This method is one of the established surgical procedures in modern shoulder surgery and represents an effective surgical treatment.

The prognosis for shoulder impingement syndrome is favorable in most cases. Patients treated with both conservative and surgical methods often experience a significant reduction in pain and a restoration of shoulder function. Studies show that long-term stable results are achieved, particularly with early treatment. Cautious mobilization begins as early as the day after surgery. The joint is not immobilized but is temporarily protected. The patient’s ability to bear weight gradually increases, and a few weeks after the procedure, a largely normal return to daily life and work is usually possible.

As with any surgical procedure, typical risks of acromioplasty include, among others, thrombosis, embolism, infections, postoperative bleeding, and—in very rare cases—injuries to nerves or blood vessels.

The procedure is performed either on an outpatient basis or with a short inpatient stay, followed by intensive physical therapy.

Given generally tight budgets, the patient’s own initiative is, of course, also required here. The affected shoulder joint is not immobilized after surgery; however, strenuous physical activity should be avoided for 3 to 4 weeks. Sports activities and overhead work should also be avoided during the first few weeks.

Mechanical constriction occurs in the area beneath the acromion, causing repeated irritation of the tendons and bursa and leading to painful inflammatory processes.

No, in many cases, consistent conservative treatment is sufficient. Surgery is only recommended if symptoms persist for a long time or if structural changes are present.

Mobility begins immediately, and full range of motion is usually regained after several weeks.

The rotator cuff is particularly at risk because its tendon runs directly through the impingement area and can be damaged by mechanical friction.

With good muscular stabilization and appropriate activity levels, the risk is low but cannot be completely ruled out.