Subacromial Syndrome
Everything you need to know about the causes, risk factors, and most effective treatments for shoulder pain.
Symptoms and Causes
Subacromial syndrome, also known as painful shoulder syndrome, is characterized by intense shoulder pain that negatively affects the patient’s quality of life, as it may even interfere with nighttime rest. This condition is named after the anatomical area where it occurs—beneath the acromion, which is a projection of the scapula that forms part of the shoulder joint.
Pain progressively increases in intensity over time as the underlying pathology evolves. This condition typically develops in three stages:
- Initial stage: edema (inflammation) and microhemorrhages in the bursa, the sac containing synovial fluid that cushions the joint during movement.
- Second stage: bursal fibrosis as a consequence of the inflammatory process and supraspinatus tendinitis.
- Final stage: osteophytosis develops, characterized by the formation of bony outgrowths on the scapula, along with tendon rupture.
Depending on the area of the shoulder affected, subacromial syndrome can be classified into two types:
- External impingement: the rotator cuff tendons and the bursa are compressed between the humeral head and the acromion when the arm is elevated.
- Internal impingement: the posterior aspect of the rotator cuff is compressed between the humeral head and the glenoid cavity (a depression located on the lateral side of the scapula) during certain movements.
The prognosis of subacromial syndrome is generally favorable, as pain significantly improves in most patients without the need for surgical intervention.
Symptoms
The main symptom of subacromial syndrome is shoulder pain, which presents differently depending on the stage of the condition:
- Initial stage: pain after exertion.
- Second stage: pain during exertion and at night.
- Final stage: persistent pain.
Pain is localized to the shoulder region but often radiates to the elbow. It typically worsens when lifting the arms above the head, reaching the hand behind the back, or lying down.
Causes
Subacromial syndrome is caused by injury to the supraspinatus tendon, which connects the supraspinatus muscle to the humerus, stabilizing the joint and enabling shoulder mobility. This condition is usually due to a narrowing of the subacromial space, which separates the humeral head from the acromion.
A reduced subacromial space may be classified into two types:
- Primary impingement: caused by structural factors, such as the development of osteophytes or changes in scapular morphology.
- Secondary impingement: arises as a consequence of other conditions, including muscle imbalances, joint instability, or alterations in shoulder biomechanics.
Risk Factors
Factors that increase the risk of developing subacromial syndrome include:
- Age: although it can occur at any age, natural tissue degeneration over time makes it more common after the age of 40.
- Osteoarthritis: degeneration of the tissues forming the joint, typically affecting individuals over 50 years of age.
- Poor vascularization of the supraspinatus tendon.
- Hook-shaped acromion: a narrower-than-normal shoulder structure.
- Bipartite acromion: although uncommon, the acromion may consist of two separate parts instead of one, leading to abnormal shoulder motion and increased tendon friction.
- Repetitive shoulder use over many years (e.g., swimming, tennis, volleyball, or occupations involving repeated arm elevation).
Complications
When subacromial syndrome is not adequately treated or does not respond as expected to therapy, it may lead to the following complications:
- Chronic inflammation.
- Rotator cuff tendon tears.
- Degeneration of articular cartilage.
- Tendon calcifications.
- Adhesive capsulitis, also known as frozen shoulder: joint stiffness and restricted range of motion.
- Muscle weakness.
- Secondary muscle contractures: painful muscle tension in the neck and back.
Prevention
Adopting healthy habits helps prevent subacromial syndrome. Specialists recommend the following measures:
- Maintain proper posture: avoid leaning forward and keep the shoulders back.
- Perform exercises to strengthen the shoulder muscles and improve flexibility.
- Avoid excessive strain and repetitive movements whenever possible.
- Allow sufficient time for joint rest between periods of intense use.
- Avoid sleeping on the painful shoulder.
Which specialist treats subacromial syndrome?
The diagnosis and therapeutic management of subacromial syndrome fall within the field of traumatology and orthopedic surgery. In most cases, physiotherapy specialists play a key role in the treatment process.
Diagnosis
The diagnosis of subacromial syndrome is based on a combination of clinical evaluation and imaging studies. The standard diagnostic approach includes:
- Medical history and anamnesis: assessment of the patient’s medical background, lifestyle, and reported symptoms.
- Physical examination: evaluation of range of motion, joint stability, and muscle strength.
- Neer impingement test: one hand stabilizes the scapula while the examiner passively elevates the straight arm. The test identifies the point at which pain occurs.
- Hawkins–Kennedy test: with the patient seated, the examiner elevates the arm forward, flexes the shoulder and elbow to 90 degrees, and internally rotates the arm to elicit pain or discomfort.
- Painful arc test: the patient slowly raises the arm with the thumb pointing upward while the examiner observes for pain between 60 and 120 degrees. Pain occurring at 180 degrees helps rule out other conditions.
- X-rays: imaging using X-rays to assess shoulder structures. The size and characteristics of the subacromial space and the shape of the acromion are evaluated to confirm or exclude the diagnosis. This test is useful for assessing bone integrity and detecting abnormalities or signs of osteoarthritis.
- Magnetic resonance imaging (MRI): magnetic fields and radio waves are used to obtain detailed images of the shoulder, allowing assessment of soft tissues such as tendons and the subacromial bursa.
Treatment
Treatment of subacromial syndrome is usually conservative, and improvement may take two to three months. Common therapeutic approaches include:
- Lifestyle modifications: avoiding movements that require lifting the arms above the head.
- Ice application to reduce inflammation.
- Anti-inflammatory treatment (NSAIDs) and analgesics to relieve pain and inflammation.
- Physiotherapy, which includes several types of exercises:
- Mobility exercises that should begin gently and gradually increase in intensity according to pain tolerance. Self-assisted stretching and supported controlled movements, such as wall-assisted arm elevation, are recommended.
- Strengthening exercises to reinforce joint stability and increase tendon resistance. These should be low-impact exercises combining gentle stretching, rotations, and pendular movements.
- Corticosteroid injections: if pain is disabling or does not improve as expected, anti-inflammatory medication is injected directly into the joint. The effects are usually temporary, and the procedure may need to be repeated after a period of time.
In patients who do not improve after six months, experience very severe pain, or require rapid recovery, a surgical procedure known as acromioplasty is performed. This is an arthroscopic surgery involving two incisions of approximately one centimeter, through which instruments are introduced to reshape the acromion and prevent tendon impingement. During the same procedure, a torn tendon may be repaired and repositioned, or the bursa may be removed if it is severely damaged.
Return to normal activities after surgery depends on occupational demands. Office-based work can usually be resumed within ten days, whereas physically demanding activities may require approximately four weeks of recovery.
