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Subacromial impingement (shoulder impingement syndrome)

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 5 minutes read

Subacromial impingement (also known as shoulder impingement syndrome) is a condition characterised by painful movement of the shoulder. Pain often occurs when moving the shoulder and arm in specific directions and can be associated with weakness.

Subacromial impingement is one of the most common causes of shoulder pain. It most commonly affects people aged 30-70 and around one in five people will experience symptoms of subacromial impingement at some time in their lives. Subacromial impingement tends to cause pain that can be felt at the top of the shoulder and can spread down the arm towards the elbow, pain worse when lifting your arm to side and above your head, weakness when lifting your arm to the side.

Where is the problem occurring?

In subacromial impingement, the rotator cuff tendons of the shoulder (which are responsible for the movement of the shoulder in different directions) become inflamed or irritated by different causes in and around the subacromial space.

The causes of subacromial impingement are not very well understood. Factors thought to contribute to the development of subacromial impingement include repetitive overuse, muscle weakness or imbalance, and the size and shape of the bony space through which the tendons pass. It is most likely that a combination of a number of these factors will result in symptoms.

Treatment Options

If you experience subacromial impingement, you do something about it. Here are our top tips and recommended treatments;

Physical Therapy

  • Strengthening exercises for the rotator cuff and scapular stabilisers can help alleviate symptoms.
  • Stretching exercises to improve flexibility and range of motion.
  • Techniques to correct posture and shoulder mechanics.

Anti-Inflammatory Medications

Corticosteroid Injections

  • Injection of cortico-steroids into the subacromial space to reduce inflammation.
  • Used judiciously due to potential side effects, injections can provide temporary relief.

Activity Modification

  • Temporarily modify or avoid activities that worsen symptoms.
  • Making adjustments to workstations and activities to reduce strain on the shoulder.

Sacrimonial Impingement vs Similar Conditions

Rotator Cuff Tears

While subacromial impingement involves compression of the rotator cuff tendons, it's distinct from a rotator cuff tear. In subacromial impingement, the tendons may be irritated and inflamed due to compression, but they are not necessarily torn. Rotator cuff tears, on the other hand, involve partial or complete ruptures of the tendon fibers. The symptoms of a tear may include weakness, a popping sensation, and, in some cases, an audible snapping sound during arm movement.

Frozen Shoulder (Adhesive Capsulitis):

Subacromial impingement primarily involves the compression of the rotator cuff tendons, leading to pain and limited range of motion. In contrast, frozen shoulder, or adhesive capsulitis, is characterised by the inflammation and thickening of the joint capsule, resulting in stiffness and restricted movement. While both conditions can cause pain and impact daily activities, the underlying mechanisms and treatment approaches differ. Frozen shoulder often requires targeted stretching exercises and physical therapy to address the joint capsule's tightness and improve mobility.

Shoulder Bursitis

Shoulder bursitis shares similarities with subacromial impingement as it involves inflammation within the shoulder joint. However, bursitis specifically targets the bursa, fluid-filled sacs that reduce friction between tendons and bones. In subacromial Impingement, the focus is on the compression of rotator cuff tendons. Bursitis can cause localised pain and swelling, typically exacerbated by overhead activities. Treatment for shoulder bursitis may involve anti-inflammatory medications, corticosteroid injections, and physical therapy, emphasising the importance of reducing inflammation within the bursa.

Glenohumeral Osteoarthritis

Glenohumeral osteoarthritis, characterised by the degeneration of the shoulder joint's articular cartilage, differs from subacromial impingement in terms of its origin and impact. Osteoarthritis involves the breakdown of the joint surfaces, leading to pain, stiffness, and reduced range of motion. While subacromial impingement is often associated with specific activities and compression of tendons, osteoarthritis may result from wear and tear over time. Treatment for osteoarthritis may include pain management, physical therapy, and, in advanced cases, joint replacement surgery.

Acromioclavicular (AC) Joint Arthritis

Similar to subacromial impingement, AC joint arthritis can cause shoulder pain, but the focus is on the acromioclavicular joint rather than the subacromial space. AC joint arthritis often presents with tenderness and swelling over the top of the shoulder. The pain may be exacerbated by activities that involve crossing the arm over the chest. While subacromial impingement consists of the compression of rotator cuff tendons beneath the acromion, AC joint arthritis is centred around degeneration and inflammation within the joint itself. Treatment approaches may include rest, anti-inflammatory medications, and, in some cases, surgical interventions to address the AC joint.

When to see your doctor?

If you develop severe shoulder pain following an injury you should seek medical attention sooner. If your shoulder pain has come on very quickly or is associated with you feeling unwell, especially with a fever, you should seek urgent medical attention.

What will my doctor do?

Your doctor will ask you about your symptoms and examine you. On occasions, your doctor may arrange an X-Ray to assess the shoulder joint for other causes of pain. If a diagnosis of subacromial impingement is made you may be given advice regarding exercises and rest to help relieve your symptoms. You may be referred to a physiotherapist in the first instance, depending upon the local services available.

If your symptoms fail to improve despite physiotherapy input or are very severe, you may be referred to an orthopaedic surgeon. Additional hospital treatments that can be offered for subacromial impingement include injections or, very rarely, surgery to remove some of the inflamed tissue and increase the size of the space around the shoulder through which the tendons pass. It is important to remember that in most cases an almost complete recovery can be expected without requiring any form of injection or surgery.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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