Subacromial Impingement and Bursitis

What is the Subacromial Space?

The subacromial space is the small area between the top of the humerus (arm bone) and the acromion (part of the shoulder blade). A fluid-filled sac called the bursa sits here to reduce friction when the shoulder moves.

What is This Condition?

• Impingement happens when the tendons of the rotator cuff or the bursa are pinched between the bones during overhead movement.

• Bursitis is when the bursa becomes irritated and inflamed, causing pain and swelling.

What Causes It?

• Repetitive overhead activity (throwing, swimming, lifting)

• Weakness or imbalance of shoulder muscles

• Bone spurs that narrow the subacromial space

• Poor posture, which changes shoulder mechanics

What are the Symptoms?

• Shoulder pain when lifting the arm overhead or reaching behind the back

• Pain that may radiate from the shoulder to the outside of the arm

• Weakness with lifting or reaching

• Pain that can worsen at night, especially when lying on the affected side

• A catching or pinching sensation with certain movements

How is It Diagnosed?

• History and exam: pain with overhead motion, positive impingement signs during testing

• X-rays: may show bone spurs or narrowing of the space

• MRI or ultrasound: can show bursitis or tendon irritation

How is It Treated?

• Rest and avoiding painful overhead activity

• Anti-inflammatory medications (NSAIDs)

• Physical therapy to strengthen rotator cuff and shoulder blade muscles

• Cortisone injection into the subacromial space for pain and inflammation

Surgery (subacromial decompression or spur removal) if symptoms don’t improve with conservative care