Yes, a bursal-surface tear extending partially into the infraspinatus tendon is definitively a rotator cuff tear—specifically, a partial-thickness rotator cuff tear.
A bursal-side tear that extends into the tendon substance represents a partial-thickness rotator cuff tear, regardless of whether it involves the supraspinatus or infraspinatus tendon. The infraspinatus is one of the four rotator cuff tendons, and any disruption of its fibers—whether on the articular surface, bursal surface, or within the tendon substance—constitutes a rotator cuff tear 1.
Understanding the Classification
The ACR Appropriateness Criteria clearly defines the spectrum of rotator cuff tears 1:
Partial-thickness tears can occur in three locations:
- Articular surface (most common type of partial tear)
- Bursal surface (superior aspect of tendon)
- Intrasubstance (within the tendon itself)
Full-thickness tears extend from the inferior (articular) to the superior (bursal) surface with increased signal intensity on all MRI sequences
Your described pathology—a bursal-surface tear extending partially into the infraspinatus—falls squarely into the partial-thickness tear category. The fact that it originates from the bursal side and extends into (but not through) the tendon makes it a bursal-side partial-thickness rotator cuff tear.
Clinical Significance
Bursal-side tears are less common than articular-side tears but are clinically significant 2, 3. These tears:
- Often present with shoulder pain, particularly with motion
- Show positive impingement signs (Neer sign in 92%, Hawkins sign in 71%) 2
- May be associated with subacromial spurs and greater tuberosity changes 4
- Can progress to full-thickness tears if untreated
Diagnostic Considerations
MRI is the preferred imaging modality, though bursal-side tears can be challenging to detect 1, 2:
- Fat-suppressed T2-weighted sequences are essential
- MRI sensitivity for bursal-side tears is approximately 74% 2
- CT bursography may be considered when MRI is equivocal 5
- Arthroscopy remains the gold standard for definitive diagnosis 2
Important Caveats
Do not confuse this with tendinosis or tendinopathy, which show signal abnormality without focal disruption 1. The key distinction is that your case describes an actual tear—a focal disruption of tendon fibers—not just degenerative signal changes.
The infraspinatus is equally part of the rotator cuff as the more commonly discussed supraspinatus. Both contribute to shoulder stability and function, and tears in either tendon warrant the same diagnostic and therapeutic consideration 6, 7.