The Subacromial Impingement Myth: Rethinking the Cause of Shoulder Pain

Melissa had always been active—playing tennis on weekends, swimming in the summer, and practicing yoga in the mornings. But lately, every time she reached overhead, a sharp pain stabbed through her right shoulder. A visit to the doctor led to an all-too-common diagnosis: subacromial impingement syndrome. The explanation seemed simple—her rotator cuff was “pinching” under the acromion, causing irritation. A cortisone shot was recommended, followed by the possibility of surgery if things didn’t improve.

But what if that explanation was outdated? What if Melissa’s pain wasn’t caused by a mechanical “pinching” at all?

The Classic Impingement Theory: A Flawed Model

For decades, subacromial impingement has been used as a catch-all diagnosis for shoulder pain, particularly when overhead movements trigger discomfort. The traditional theory suggests that the rotator cuff tendons and subacromial bursa become compressed between the humeral head and the acromion, leading to irritation and inflammation. This model has fueled countless surgical procedures aimed at “creating more space” in the shoulder by shaving down the acromion or removing the bursa.

However, newer research suggests that structural impingement may not be the primary driver of pain. A growing body of evidence challenges the necessity of these surgical interventions and points to other factors—neurological adaptation, movement patterns, and systemic inflammation—as more significant contributors to shoulder pain.

What Does the Research Say?

Recent studies have revealed some surprising findings about subacromial impingement:

• MRI and Ultrasound Studies Show “Impingement” in Pain-Free Individuals

  • Research published in the British Journal of Sports Medicine found that up to 50% of asymptomatic individuals have signs of rotator cuff tears, bursitis, or tendon thickening on imaging.

  • If structural impingement were the main cause of pain, why do so many people with the same anatomical features remain pain-free?

• Surgery Often Yields No Better Results Than Placebo

  • A 2017 study in The Lancet compared outcomes between patients who had subacromial decompression surgery and those who had a placebo surgery (where the surgeons made incisions but performed no actual procedure). The results? No significant difference in pain relief between the two groups.

  • This suggests that the mechanical “pinching” theory may not be the true source of pain.

• The Nervous System’s Role in Shoulder Pain

  • Chronic pain often involves central sensitization, where the nervous system amplifies pain signals, even in the absence of tissue damage.

  • Studies have shown that altered movement patterns and compensatory strategies play a larger role in shoulder dysfunction than previously thought.

Alternative Explanations for Shoulder Pain

If impingement isn’t the main cause, then what is? Here are some of the more scientifically supported explanations for persistent shoulder pain:

1. Neuromuscular Control Deficits

• Weakness or improper activation of the rotator cuff and scapular stabilizers can lead to inefficient movement, resulting in irritation.

• Addressing muscle imbalances through targeted rehab often provides more relief than structural interventions.

2. Movement Variability and Coordination Issues

• Many people with shoulder pain develop compensatory movement patterns that increase strain on the joint.

• Improving motor control and restoring natural shoulder rhythm can significantly reduce discomfort.

3. Inflammatory Processes and Sensory Changes

• Chronic low-grade inflammation can heighten pain sensitivity, even in the absence of direct mechanical irritation.

• Nutritional strategies, chiropractic care, and manual therapy can help regulate inflammation and desensitize the nervous system.

4. Central Sensitization and Brain Processing of Pain

• The brain can maintain pain signals long after an initial injury has healed, creating an ongoing cycle of discomfort.

• Techniques like graded motor imagery, proprioceptive retraining, and chiropractic adjustments can help recalibrate the nervous system.

What This Means for Treatment

The outdated impingement model has led to an over-reliance on surgery and cortisone injections, which often provide only temporary relief or no benefit at all. Instead, a more effective approach focuses on restoring optimal movement patterns, strengthening neuromuscular control, and addressing pain from a whole-body perspective.

1. Strengthen and Retrain Shoulder Stabilizers

• Exercise interventions focusing on rotator cuff activation and scapular control help improve dynamic stability and reduce strain.

2. Chiropractic and Manual Therapy

• Dr. Noah Volz in Ashland, OR, uses evidence-based chiropractic techniques to improve shoulder function and address neurological contributors to pain.

3. Pain Education and Movement Re-Education

• Learning that pain is not always linked to damage can reduce fear and promote confidence in movement.

• Proprioceptive retraining, graded exposure, and sensory feedback exercises can help the brain relearn safe shoulder movement.

4. Address Inflammation and Lifestyle Factors

• Diet, sleep quality, and stress all play roles in pain perception. Anti-inflammatory nutrition and stress-reducing techniques can improve recovery.

Melissa’s Journey: A New Perspective on Shoulder Pain

Melissa was hesitant when she first heard that her shoulder pain might not be due to impingement. But after working with Dr. Noah Volz in Ashland, OR, she started focusing on movement retraining, stability exercises, and nervous system regulation instead of worrying about “creating more space” in her joint. Within a few months, her pain had significantly decreased—without surgery or cortisone injections.

The Takeaway: Moving Beyond the Impingement Myth

For years, the subacromial impingement model has guided treatment decisions, often leading patients down a path of unnecessary procedures. But new research shows that pain is more about movement, nervous system sensitivity, and function than about simple structural changes. By shifting the focus from mechanical pinching to optimizing movement and addressing neurological components, patients can achieve long-term relief—without invasive interventions.

If you’re struggling with shoulder pain and have been told you have “impingement,” consider exploring a more holistic, science-based approach. With the right guidance, you can move beyond the myth and take control of your recovery.