Overview
Shoulder impingement is one of the most common causes of shoulder pain. It occurs when the rotator cuff becomes irritated by rubbing beneath the acromion during overhead activities. Patients commonly experience pain with reaching overhead, lifting, and often pain at night. Shoulder impingement is frequently the beginning of a process that may improve with treatment or gradually progress to a partial or full-thickness rotator cuff tear if left untreated.
The rotator cuff is made up of four muscles—the supraspinatus, infraspinatus, teres minor, and subscapularis. As the arm is raised, particularly during overhead activities, the rotator cuff passes through a naturally tight space beneath the acromion. This area is especially prone to irritation because of both the close fit and the relatively limited blood supply to part of the rotator cuff. As irritation develops, inflammation increases, making the tendon even more sensitive. Pain often fluctuates with activity—many patients improve with rest but notice worsening symptoms after repetitive overhead use or heavier activities. Night pain is especially common and is often one of the first symptoms that brings patients into the office.
I often compare shoulder impingement to wearing a shoe that rubs the back of your heel. At first, the shoe may simply feel tight. As a blister develops, however, the rubbing becomes more painful. More rubbing creates a larger blister, which leads to even more irritation, creating a vicious cycle. The same process can occur in the shoulder. When conservative treatment is unsuccessful, arthroscopically increasing the space beneath the acromion is much like relieving the pressure from the back of the shoe—it breaks the cycle of irritation.
Presentation
Patients with shoulder impingement commonly complain of pain reaching overhead, lifting objects away from the body, or performing repetitive activities. Night pain is extremely common and often makes it difficult to sleep on the affected side.
Symptoms frequently develop gradually rather than after a specific injury. Many patients notice periods where the shoulder feels much better with rest, only to have the pain return once activity increases. If left untreated, persistent impingement may progress to a partial or complete rotator cuff tear.
Conservative Treatment
- Rest and activity modification
- Ice
- Anti-inflammatory medications when appropriate
- Maintain shoulder range of motion
If symptoms persist for more than several weeks, a professional evaluation is appropriate.
Therapy: Focus on maintaining motion, strengthening the rotator cuff, especially external rotation strength, and improving shoulder mechanics.
Subacromial Corticosteroid Injection: In selected patients, a corticosteroid injection can significantly reduce inflammation and pain, often allowing therapy to be more effective.
Surgical Treatment
When symptoms persist despite appropriate conservative treatment, arthroscopic subacromial decompression may be recommended. A small amount of bone is removed from the undersurface of the acromion, increasing the available space for the rotator cuff and relieving the pressure responsible for the ongoing irritation.
The decompression itself typically takes about 10 minutes, although the overall surgery often lasts 30–45 minutes because other shoulder problems are frequently addressed during the same procedure. Surgery is performed on an outpatient basis. When decompression is performed by itself, patients begin using the shoulder almost immediately, with most recovering over one to three months.