Internal impingement is a condition that causes shoulder pain from within the joint. Unlike the more well-known subacromial impingement, which involves structures on the outside of the rotator cuff, internal impingement occurs when the rotator cuff rubs or gets pinched against the deeper parts of the shoulder, such as the labrum or the glenoid. This rubbing can cause pain, fraying, or even tears in the rotator cuff and labrum.
Internal impingement can be anterior (front of the shoulder) or posterior (back of the shoulder), and it can occur in both athletes and non-athletes. Arthroscopy—using a camera inside the joint—helps visualize and treat these issues precisely and minimally invasively.
What Is Internal Impingement?
Internal impingement is the abnormal contact between the undersurface of the rotator cuff and the glenoid labrum (the cartilage ring around the shoulder socket). This contact can be painful, especially during certain arm positions such as when the arm is lifted and rotated.
There are two main types:
- Posterior internal impingement often affects throwing athletes. The back of the rotator cuff pinches against the back of the shoulder socket.
- Anterior internal impingement is less well-known and can occur in non-athletes. The front part of the rotator cuff rubs against the front of the labrum.
In both cases, the impingement causes the rotator cuff to fray or tear, and sometimes the labrum becomes irritated or detaches slightly.
What Are the Symptoms?
Patients with internal impingement often report:
- Shoulder pain, especially during overhead movements or lifting the arm forward
- Pain while sleeping, especially on the affected side
- Popping, clicking, or catching in the shoulder
- Stiffness and decreased range of motion
- Pain during certain physical tests, such as the Hawkins or Neer test
Athletes, especially throwers, may notice a decline in performance or feel like their arm “just doesn’t work the same.”
Why Is It Difficult to Diagnose?
Internal impingement is tricky to diagnose because the symptoms are very similar to subacromial impingement, and traditional imaging like MRI often misses the actual cause. In many cases, the MRI may look normal, even though the patient has a partial rotator cuff tear or labral injury.
During arthroscopy, however, the surgeon can directly observe the impingement. This is particularly true when a maneuver like the Hawkins test is performed under direct camera view—this allows the surgeon to see the torn rotator cuff being pinched against the labrum.
Real Case Example
One patient was a 35-year-old man with six weeks of shoulder pain that worsened over time. He experienced painful popping and couldn’t play golf anymore. Despite having normal shoulder stability and a negative MRI, arthroscopy revealed a partial tear of the rotator cuff. When the surgeon lifted and rotated his arm during the procedure, the torn edge of the rotator cuff rubbed directly against the labrum. This was the true source of his pain. After the torn tissue was cleaned out (debrided), the rubbing stopped and he fully recovered within a month.
What Does Arthroscopic Surgery Involve?
Arthroscopic treatment of internal impingement typically includes:
- Diagnostic arthroscopy – The surgeon inserts a small camera into the joint to inspect the rotator cuff, labrum, and surrounding tissues.
- Debridement – Any frayed or damaged tissue is carefully shaved or cleaned.
- Labral repair – If the labrum is detached or frayed, it can be reattached using small anchors.
- Avoiding unnecessary surgery – In many cases, acromioplasty (shaving bone above the rotator cuff) is not needed, since the problem is inside the joint and not above it.
What Does Recovery Look Like?
After surgery, most patients:
- Go home the same day
- Use a sling for a short time
- Begin gentle physical therapy within a few days to weeks
- Return to regular activity within a month or two, depending on the severity
In the series of cases reviewed, the majority of patients regained full motion and were free of pain. A few had mild symptoms with strenuous activity, and only one person—who also had arthritis—did not improve significantly.
When to Suspect Internal Impingement
This condition should be considered when:
- A young or middle-aged person has shoulder pain that does not respond to therapy
- The MRI is negative or inconclusive
- There is pain during forward elevation and rotation of the arm
- The shoulder is stable, but painful with certain positions
It is also common in athletes, especially throwers, who develop shoulder pain at the end of their throwing motion.
How Is It Different from Other Shoulder Problems?
Unlike subacromial impingement (which involves structures above the rotator cuff), internal impingement happens deeper in the joint. The pain pattern and exam findings can look similar, but the source of pain is different. In internal impingement, the rotator cuff gets pinched between the humeral head (ball of the shoulder) and the glenoid (socket). This usually happens when the arm is lifted and turned inward or outward.
Why Arthroscopy Is the Best Tool
Internal impingement is often missed by MRI or physical exam. Arthroscopy allows the surgeon to:
- See the impingement happen in real time
- Identify exactly which part of the rotator cuff or labrum is involved
- Tailor the treatment precisely to the patient’s anatomy
- Avoid over-treating or under-treating the condition
For patients with unresolved pain and a normal MRI, arthroscopy often provides answers and relief.
Final Thoughts
Internal impingement is a common but underrecognized source of shoulder pain, especially in young patients and athletes. It often mimics other shoulder problems and can go undiagnosed for months. When treated properly—especially with arthroscopy—most patients recover well and return to normal activity.
If you or someone you know is struggling with shoulder pain that hasn’t improved with therapy, and imaging studies are unclear, consider speaking with a shoulder specialist. Arthroscopic evaluation may reveal a hidden cause that can be treated simply and effectively.
Do you have more questions?
Q. What is internal impingement of the shoulder?
A. Internal impingement is a condition where the rotator cuff tendons get pinched between the humeral head and the glenoid when the arm is in an abducted and externally rotated position.
Q. What causes internal impingement?
A. It is commonly seen in overhead athletes and results from repetitive throwing or overhead activities that lead to pinching of the rotator cuff tendons.
Q. What are the symptoms of internal impingement?
A. Symptoms include shoulder pain during overhead activities, decreased performance, and sometimes clicking or a catching sensation.
Q. How is internal impingement diagnosed?
A. Diagnosis is based on a detailed history, physical examination, and imaging studies such as MRI to evaluate the rotator cuff and labrum.
Q. What non-surgical treatments are available for internal impingement?
A. Non-surgical options include rest, activity modification, physical therapy, anti-inflammatory medications, and sometimes injections.
Q. When is surgery considered for internal impingement?
A. Surgery is considered if non-surgical treatments fail to relieve symptoms and the patient has ongoing pain and loss of function.
Q. What does arthroscopic treatment of internal impingement involve?
A. The procedure involves debridement or repair of the rotator cuff and labrum, removal of inflamed tissue, and addressing any contributing pathology.
Q. What is the recovery time after arthroscopic treatment?
A. Recovery time varies but generally involves a period of rest, followed by physical therapy to regain motion and strength.
Q. Will I need physical therapy after surgery?
A. Yes, physical therapy is essential after surgery to help restore shoulder motion, strength, and function.
Q. Can athletes return to sports after arthroscopic treatment for internal impingement?
A. Many athletes are able to return to their sport after completing rehabilitation and regaining full shoulder function.
