Rotator Cuff Problems and Shoulder Impingement: How Do We Know Which Tendon Is Involved?
Shoulder pain can be confusing. You may be told that you have a “rotator cuff problem,” “shoulder impingement,” or “tendonitis.” But what do these terms actually mean?
Is rotator cuff pain the same as shoulder impingement?
Not exactly. Shoulder impingement is a clinical term that has historically been used to describe pain associated with structures around the rotator cuff and subacromial region. Rotator cuff tendinopathy, partial tears, bursitis and other shoulder problems can produce similar symptoms. Therefore, simply being told that you have “impingement” does not necessarily mean that one particular tendon is damaged.
1. Supraspinatus: The Shoulder's Lifting Muscle
What might suggest supraspinatus involvement?
During an assessment, your therapist may look for:
Painful arc:
Pain occurs during a particular portion of active shoulder elevation, commonly around the middle range.
Pain or weakness with resisted shoulder abduction:
The therapist asks you to lift your arm while they apply resistance.
Pain with passive elevation:
The therapist moves your arm for you and assesses whether symptoms occur near the end of the available range.
These findings can be consistent with rotator cuff-related shoulder pain, but no single test can confirm that the supraspinatus is definitely the source of the problem.
1. Supraspinatus: The Shoulder's Lifting Muscle
What might suggest supraspinatus involvement?
During an assessment, your therapist may look for:
Painful arc:
Pain occurs during a particular portion of active shoulder elevation, commonly around the middle range.
Pain or weakness with resisted shoulder abduction:
The therapist asks you to lift your arm while they apply resistance.
Pain with passive elevation:
The therapist moves your arm for you and assesses whether symptoms occur near the end of the available range.
These findings can be consistent with rotator cuff-related shoulder pain, but no single test can confirm that the supraspinatus is definitely the source of the problem.
Could the supraspinatus be completely torn?
A full-thickness rotator cuff tear can produce significant weakness.
A clinician may become more concerned about a substantial tear when there is:
- Marked weakness during resisted abduction
- Weakness that is not simply explained by pain
- Difficulty actively lifting the arm
- A significant difference in strength compared with the other shoulder
- Loss of active movement
Importantly, painful or limited movement alone does not prove a complete tendon rupture.
2. Infraspinatus: The External Rotator
What might suggest infraspinatus involvement?
Your therapist may assess:
Painful arc:
Pain during a particular portion of shoulder elevation.
Resisted external rotation:
You are asked to rotate your forearm outward while the therapist provides resistance.
Pain with passive elevation:
The therapist moves the arm and assesses the range and location of your symptoms.
Again, these findings are interpreted together rather than individually.
How might a major infraspinatus tear present?
A significant tear affecting the external rotators may result in:
- Marked weakness with external rotation
- Difficulty actively rotating the arm outward
- Reduced active external rotation
- Difficulty maintaining the arm in an externally rotated position
One clinical test that may be used is the Hornblower’s sign.
During this test, the arm is positioned with the elbow bent and the shoulder elevated. The patient attempts to maintain external rotation.
Inability to maintain the position or marked weakness can suggest significant dysfunction of the external rotators, particularly the teres minor and/or infraspinatus.
3. Subscapularis: The Internal Rotator
What might suggest subscapularis involvement?
Your clinician may assess:
- Pain with resisted internal rotation
- Pain during certain shoulder movements
- Weakness with internal rotation
What About Calcific Rotator Cuff Tendinopathy?
Sometimes calcium deposits develop within a rotator cuff tendon. This is called calcific tendinopathy or calcific tendonitis.
Is high-energy shockwave therapy the only effective treatment?
This is an important point to clarify.
High-energy extracorporeal shockwave therapy (ESWT) is one treatment option for calcific rotator cuff tendinopathy, but it is not accurate to say that it is the only effective treatment.
This article is for educational purposes and does not replace an individual assessment by a qualified healthcare professional.