Understanding the Connection Between Subacromial Impingement and Shoulder Pain

Shoulder pain is a common complaint that affects millions of people worldwide. One frequent cause of this discomfort is subacromial impingement, a condition that can significantly limit shoulder movement and quality of life. Understanding why subacromial impingement causes shoulder pain helps in recognizing symptoms early and seeking appropriate treatment.

Illustration of the shoulder joint showing the subacromial space and impingement area

What Is Subacromial Impingement?

Subacromial impingement occurs when the tendons of the rotator cuff muscles or the bursa (a fluid-filled sac that reduces friction) get compressed or pinched between the acromion (a bony projection on the shoulder blade) and the head of the humerus (upper arm bone). This space is called the subacromial space.

When this space narrows due to inflammation, bone spurs, or repetitive overhead activities, the soft tissues become irritated. This irritation leads to pain, swelling, and reduced shoulder mobility.

Why Does Subacromial Impingement Cause Pain?

The pain from subacromial impingement arises mainly from inflammation and damage to the soft tissues in the shoulder. Here’s how it happens:

• Tendon irritation: The rotator cuff tendons rub against the acromion repeatedly, causing micro-tears and inflammation.

• Bursa inflammation: The bursa becomes swollen and painful as it tries to protect the tendons from friction.

• Nerve sensitivity: Inflamed tissues can irritate nearby nerves, increasing pain signals.

• Reduced blood flow: Compression can limit blood supply to the tendons, slowing healing and increasing discomfort.

  
  

This combination of factors creates a cycle of pain and stiffness that worsens with shoulder movement, especially when lifting the arm overhead.

Common Symptoms of Subacromial Impingement

Recognizing symptoms early can prevent further damage. Common signs include:

• Pain when lifting the arm: Especially between 60 and 120 degrees of elevation.

• Weakness: Difficulty lifting or rotating the arm.

• Tenderness: Pain when pressing on the front or side of the shoulder.

• Night pain: Discomfort that worsens when lying on the affected side.

• Limited range of motion: Stiffness and difficulty reaching behind the back or overhead.

  
  

Who Is at Risk?

Certain activities and conditions increase the risk of developing subacromial impingement:

• Repetitive overhead movements: Common in athletes like swimmers, throwing athletes, racquet sports and painters.

• Age-related changes: Tendons weaken and bursa thickens with age.

• Poor posture: Rounded shoulders reduce the subacromial space.

• Previous shoulder injuries: Can lead to scar tissue and narrowing of the space.

• Bone spurs: Extra bone growth on the acromion can pinch soft tissues.

  
  

How Is Subacromial Impingement Diagnosed?

Doctors diagnose this condition through a combination of:

• Medical history: Discussing symptoms and activities.

• Physical exam: Testing shoulder movement and strength.

• Imaging tests: X-rays to check bone spurs, MRI or ultrasound to view soft tissues.

• Special tests: Specific arm movements that reproduce pain help confirm impingement.

  
  

Treatment Options for Shoulder Pain Due to Subacromial Impingement

Treatment focuses on reducing pain, improving shoulder function, and preventing further damage. Options include:

• Rest and activity modification: Avoiding overhead activities that worsen symptoms.

• Physical therapy: Exercises to strengthen rotator cuff muscles and improve posture.

• Anti-inflammatory medications: To reduce swelling and pain.

• Corticosteroid injections: For severe inflammation.

• Surgery: In cases where conservative treatments fail, procedures like acromioplasty remove bone spurs and increase the subacromial space.

  
  

Preventing Subacromial Impingement

Prevention involves maintaining shoulder health through:

• Regular exercise: Strengthening shoulder muscles and improving flexibility.

• Proper technique: Using correct form during sports or work activities.

• Posture awareness: Keeping shoulders back and avoiding slouching.

• Early treatment: Addressing shoulder pain promptly to avoid worsening.

  
  

Real-Life Example

Consider a recreational tennis player who starts experiencing sharp shoulder pain when serving. Ignoring the pain, the player continues training, which leads to worsening symptoms and limited arm movement. After a medical evaluation, the diagnosis is subacromial impingement caused by repetitive overhead serving motions. With physical therapy focusing on rotator cuff strengthening and activity modification, the player gradually returns to pain-free tennis.

This example shows how understanding the cause of shoulder pain can guide effective treatment and recovery.

Final Thoughts on Subacromial Impingement and Shoulder Pain

Subacromial impingement is a common source of shoulder pain caused by the compression of tendons and bursa in a narrow space. Recognizing symptoms early and seeking proper care can prevent long-term damage and restore shoulder function. If you experience persistent shoulder pain, especially with overhead movements, consult a healthcare professional for evaluation and treatment.