Shoulder pain is one of the most common musculoskeletal complaints, especially among individuals who engage in repetitive overhead movements – whether at work, in sports, or during everyday activities. Among the diagnoses associated with shoulder discomfort, Subacromial Impingement Syndrome (SIS) has long stood as a primary suspect. But growing evidence and evolving clinical perspectives, many are beginning to ask: Is shoulder impingement a real diagnosis – or an outdated myth?
In this article, we explore the history, biomechanics, current research, and treatment options for subacromial impingement syndrome. Whether you’re a patient dealing with shoulder pain or a healthcare provider seeking clarity, this blog will help demystify the concept.
What Is Subacromial Impingement Syndrome?
Subacromial impingement syndrome refers to a condition in which the tendons of the rotator cuff, particular the supraspinatus tendon, are thought to become compressed or “impinged” between the head of the humerus (upper arm bone) and the acromion, the bony part of the shoulder blade.
This concept originated in the 1930s and became a dominant theory in explaining shoulder pain. The idea is that repetitive overhead movements cause the subacromial space (the space between the humeral head and the acromion) to narrow, leading to mechanical irritation, inflammation, and eventual tearing of the rotator cuff tendons.
But is it really that simple?
Traditional Understanding vs Emerging Evidence
For decades, clinicians have diagnosed and treated shoulder impingement based on this mechanical “pinch” model. However, research over the past two decades has challenged this theory. Let’s break it down.
Intrinsic vs Extrinsic Causes of Rotator Cuff Tendon Damage
New studies suggest that rotator cuff pathology may not be primarily caused by external compression, but rather by a combination of intrinsic (internal) and extrinsic (external) factors:
- Intrinsic factors include age-related tendon degeneration, reduced blood supply, metabolic changes, and the natural inability of some tendons to heal effectively.
- Extrinsic factors involve mechanical stress from repetitive movements, poor posture, muscle imbalances, or external load from work or sport.
In fact, a 2011 narrative review highlighted several studies showing that the underside (articular side) of the rotator cuff tendons – not the upper (bursal) side closer to the acromion – is most commonly affected in tears. This directly contradicts the impingement theory, which would predict the superior side being more frequently damaged due to contact with the acromion.
Mechanical Loading and Tendon Rupture
Further biomechanical research has reinforced this idea. One study investigated tendon failure under stress and found that ruptures typically begin in the deeper fibres of the rotator cuff, which are under the highest tensile load during activity. These findings point to intrinsic degeneration and overuse, rather than external compression, as primary contributors to rotator cuff injuries.
Are Subacromial Decompression Surgeries Effective?
One of the most significant implications of challenging the impingement theory is the reconsideration of surgery – specifically, subacromial decompression or acromioplasty.
What is Acromioplasty?
Acromioplasty is a surgical procedure that involves shaving or removing a portion of the underside of the acromion to widen the subacromial space and reduce “impingement.” It was believed that doing so would protect the rotator cuff tendons from further damage.
However, clinical outcomes have failed to support this approach.
A nine-year follow-up study of 96 patients who underwent acromioplasty found that 20% experienced progression of rotator cuff disease. More importantly, randomised controlled trials have repeatedly shown that acromioplasty provides no added benefit over conservative (non-surgical) care such as physiotherapy and exercise.
Rethinking Diagnosis: Is “Shoulder Impingement” Still a Useful Label?
Given the evidence, many experts argue that the term “shoulder impingement” may no longer be accurate or helpful. Labelling shoulder pain as impingement can imply a purely mechanical problem that may require surgical intervention – when in fact, the pain may stem from multiple overlapping causes including tendon overload, weakness, or lack of movement variability.
Moreover, studies have shown that patients respond just as well (if not better) to education, load management, and guided exercise programs as they do to surgery or injections.
At Logan Physio, we believe in using up-to-date, evidence-based approaches that go beyond old diagnostic labels. Rather than focusing on “impingement”, we take a holistic view of shoulder function, identifying movement patterns, strength deficits, postural habits, and lifestyle factors that contribute to discomfort.
How Is Shoulder Pain from “Impingement” Managed?
If you’re experiencing shoulder pain that’s been diagnosed as impingement – or suspect you may have it – the good news is that conservative management is highly effective for most people. Here’s what you can expect:
1. Physiotherapy-Led Exercise
Exercise therapy, especially tailored by a physiotherapist, has consistently shown to improve pain, strength, and range of motion in patients with rotator cuff-related pain.
These exercises may include:
- Rotator cuff and scapular strengthening
- Postural training
- Mobility work for the thoracic spine and shoulders
- Movement pattern re-education
2. Activity Modification
Temporary adjustments to your daily activities – such as avoiding repeated overhead movements – can help reduce strain and irritation. This doesn’t mean complete rest, but smart rest and graded reloading.
3. Manual Therapy
Hands-on techniques like joint mobilisations or soft tissue release may be used by your physiotherapist to support pain relief in the early stages of treatment.
4. Education
Understanding that your shoulder pain is not necessarily due to damage or something “being out of place” is empowering. Reassurance, load management advice, and a positive outlook are all key components of successful recovery.
5. Injections (If Needed)
In come cases, a corticosteroid injection into the subacromial space may be considered to reduce inflammation. However, these should be used judiciously and always as an adjunct to active rehabilitation, not a standalone solution.
So… Myth or Fact?
Is subacromial impingement syndrome a myth? The answer is both yes and no. While it’s clear that external compression from the acromion is unlikely to be the sole or even main cause of rotator cuff pathology, the symptoms people experience – pain with overhead movement, weakness, or stiffness – are very real.
What’s changing is how we understand and explain these symptoms, and more importantly, how we treat them. We are moving away from outdated mechanical models and toward a multifactorial, function-based approach that reflects the complexity of shoulder pain.
Final Thoughts: Where Do We Go From Here?
It’s time we evolve our language, diagnoses, and treatment strategies for shoulder pain. At Logan Physio, we encourage both clinicians and patients to view the shoulder not as a fragile joint susceptible to being pinched, but as a robust and adaptable structure capable of healing and thriving with the right guidance.
If you’ve been told you have shoulder impingement, don’t panic. It’s likely that with a thoughtful, personalised rehab plan – and a little patience – you can return to the activities you love without surgery.
Looking for Shoulder Pain Relief in Logan?
Our experienced team at Logan Physio specialises in shoulder rehabilitation and rotator cuff injuries. We use evidence-based strategies to guide your recovery, including hands-on therapy, exercise prescription, and injury education.
