What is a Partial-Thickness Supraspinatus Tear?
A partial-thickness supraspinatus tear is a form of rotator cuff tendinopathy characterized by incomplete disruption of tendon fibers—it is neither an arthropathy (joint disease) nor simple tendinopathy (tendon degeneration without tear), but rather represents an actual structural tear that does not extend through the full thickness of the tendon. 1
Understanding the Terminology
The distinction between these terms is clinically important:
Tendinosis/Tendinopathy: When imaging shows signal intensity abnormalities in the tendon without focal disruption, these terms describe underlying tendon degeneration or inflammation—a chronic degenerative process without an actual tear 1
Partial-Thickness Tear: An actual structural disruption involving only part of the tendon thickness, which can occur at three locations 1:
- Articular surface (deep/undersurface) - most common type
- Bursal surface (superficial/top surface)
- Intrasubstance (within the tendon itself)
Arthropathy: Joint disease—not applicable to tendon tears
Alternative Terminology You May Encounter
PASTA lesion (Partial Articular Supraspinatus Tendon Avulsion) specifically refers to articular-sided partial tears 2, 3. This is the most commonly used alternative term in orthopedic literature.
Clinical Context
Partial-thickness tears in patients over age 35 typically reflect injury superimposed on pre-existing tendon degeneration 4. These tears are associated with:
- Documented traumatic injury (more common than in pure tendinopathy)
- Biceps tendon degeneration
- Joint synovitis
- Tendon lengthening, suggesting "failure in continuity" 5
This represents a fundamentally different pathology than the isolated tendinopathy seen in younger overhead athletes, where the term may describe overuse injury without structural tear.
Diagnostic Imaging Considerations
MR arthrography provides the highest sensitivity for detecting partial-thickness tears, particularly articular surface tears 6. Standard MRI has lower sensitivity for partial tears compared to full-thickness tears 6. Ultrasound performance is variable and operator-dependent for partial tears, though it performs well for full-thickness tears 6.
The key imaging distinction: tendinopathy shows diffuse signal changes without focal disruption, while partial-thickness tears demonstrate actual fiber discontinuity on at least one surface of the tendon 1.