Abnormalities on MRI of the subscapularis tendon in the presence of a full-thickness supraspinatus tendon tear.
OBJECTIVE
Our objective was to determine the association between size and chronicity of full-thickness supraspinatus tendon tears with subscapularis tendon abnormalities on MRI.


METHODS
One hundred forty-two MRI examinations with full-thickness supraspinatus tendon tears were categorized on the basis of the supraspinatus muscle (SS): normal muscle (SS(normal)), suggesting a recent or small tear; reduced muscle bulk without fatty atrophy (SS(volume loss)); and those with fatty atrophy, suggesting a large or chronic tear (SS(fatty atrophy)). Subscapularis tendon abnormalities, the subcoracoid interval, and subcortical bone marrow edema in the lesser tuberosity and coracoid process were recorded.


RESULTS
The mean size of supraspinatus tendon tears in the SS(normal) (n = 45) group was 8.5 mm, 16.6 mm in SS(volume loss) (n = 53), and 29 mm in the SS(fatty atrophy) group (n = 44). Subscapularis tendon abnormality was identified in 22% of SS(normal) patients, 61% of SS(volume loss), and 86% of the SS(fatty atrophy) group (p < 0.001). There was moderate correlation between chronicity of supraspinatus tendon tears and subscapularis tendon abnormality (r = 0.47; p < 0.0001), with no correlation between the subcoracoid interval and abnormalities of the subscapularis tendon. There was moderate correlation between chronicity of supraspinatus tendon tears and bone marrow changes in the lesser tuberosity (r = 0.44; p < 0.0001).


CONCLUSIONS
Subscapularis tendon abnormality is related to chronicity of supraspinatus tendon tears. Bone marrow edema in the lesser tuberosity with a subscapularis tendon abnormality suggests increased stress at the subscapularis tendon insertion with chronicity of full-thickness supraspinatus tendon tears. Lack of correlation with the subcoracoid interval indicates that anterior instability may be a more important contributing factor to subscapularis tendon abnormalities than static subcoracoid impingement in the setting of a full-thickness supraspinatus tendon tear.
Bergin
Diane
D
Department of Radiology, Thomas Jefferson University Hospital, 396C Main Building, 111 S 10th St., Philadelphia, PA 19107.
Parker
Laurence
L
Zoga
Adam
A
Morrison
William
W
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D000070599:Shoulder Injuries; D013708:Tendon Injuries / Q000175:diagnosis*