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MRI OF SUBSCAPULARIS TEARS, ATROPHY, FATTY INFILTRATION, & BICEPS DISLOCATION
WHAT TO LOOK FOR ON MRI IN SUBSCAPULARIS TEARS, ATROPHY, FATTY INFILTRATION, & BICEPS DISLOCATION
MRI Assessment of the subscapularis tendon is not just about looking for tears. This post looks at the four things that should be assessed.Â
- The MRI appearance of partial and full-thickness tears.
 - Then assessing for muscle atrophy and fatty infiltration to determine prognosis from any tendon repair.
 - And looking for secondary biceps subluxation or dislocation and understanding the importance of the subscapularis insertion to biceps tendon stability.
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WHAT TO ASSESS FOR ON MRI
MRI SUBSCAPULARIS TEAR AXIAL
- PDFS axial demonstrates increased fluid type signal at the Subscapularis Tendon insertion in keeping with a deep surface partial tear.
- Deep surface is where the tears commonly begin.
- Look for discontinuity of tendon fibers and increased fluid type signal intensity on T2 or PD Fat Sat (T2FS/ PDFS) images.
MRI SUBSCAPULARIS TEAR SAGITTAL
- T2FS sagittal demonstrates increased fluid type signal at the Subscapularis Tendon insertion in keeping with a deep surface tear.
- I find the sagittal scans much better to spot tears before I look at the axial scans.
- Look for discontinuity of tendon fibres and increased fluid type signal intensity on T2 or PD Fat Sat (T2FS/ PDFS) images.
MRI SUBSCAPULARIS ATROPHY & FATTY INFILTRATION
Muscle atrophy and fatty infiltration are two important findings to look for in any rotator cuff tendon tear.
- MUSCLE ATROPHY,
- Look for reduction in size of the muscle and reduction in muscle fibres.
- For subscapularis this is best assessed on Sagittal T1 pr PD scans.
- Do not assess on axial or Fat saturated images as its harder.
- Extent of muscle atrophy important to report as it affects prognosis of tendon repairs.
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- FATTY INFILTRATION,
- Occurs after atrophy commences
- Fat cells infiltrate the muscle belly.
- Look for increased T1 or PD signal in the muscle.
- For subscapularis this is best assessed on Sagittal scans.
- Do not assess on axial or Fat saturated images. Fat saturation will remove the fat signal and you can’t assess the amount of fatty infiltration.
- Extent of fatty infiltration important to report as it affects prognosis of tendon repairs.
SUBSCAPULARIS TEAR BICEPS SUBLUXATION
- Axial scan. Biceps tendon (Both pink arrows) medially subluxed and perched on top of the medial margin of the bicipital groove (Green arrow).
- This was a result of a subscapularis tear (not shown). See the next tab that explains how a subscapularis tear and biceps subluxation/dislocation are connected.
- Increased intermediate signal in the biceps tendon from tendonosis.
BICEPS DISLOCATION. WHY SUBSCAPULARIS IS IMPORTANT
- Wonderful histological image of the relationship of subscapularis attachment to the biceps tendon in the bicipital groove where subscapularis forms a medial wall and prevents medial movement of biceps.
- This explains why a tear of subscap can result in medial subluxation/dislocation of the biceps tendon.
Image from: Tamborrini G et al. The Rotator Interval Ultrasound Int Open 2017; 3: E107–E116.
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