Contribution of full-thickness supraspinatus tendon tears to acquired subcoracoid impingement.
OBJECTIVE
To assess the relationship between the severity of full-thickness supraspinatus tendon tears and the development of subcoracoid impingement.


METHODS
Fifty-one magnetic resonance imaging (MRI) shoulder examination reports with full-thickness supraspinatus tears were retrospectively identified and reviewed by two dedicated musculoskeletal radiologists. The appearances of the rotator cuff muscles, biceps tendon and the lesser tubercle were recorded. The acromio-humeral distance and the axial coraco-humeral distance were measured. The data were recorded and analysed electronically.


RESULTS
The kappa values for inter-observer agreement were: 0.91 for acromio-humeral distance and 0.85 for coraco-humeral distance measurements. Twenty-six patients had significant retraction of the supraspinatus tendon, 85% (22 cases) of this group had imaging evidence of tear or tendonopathy of the subscapularis tendon. Twenty-five patients had no significant retraction of the supraspinatus, 56% (14 cases) of this group had imaging evidence of a subscapularis tear or tendonopathy. The acromio-humeral distance was significantly less in patients with supraspinatus tears and retraction (p<0.05). The subscapularis tendon was significantly more likely to be abnormal if the supraspinatus was retracted than if no retraction was present (p<0.05). There were no significant differences in coraco-humeral distances between the groups.


CONCLUSIONS
Subscapularis tendon signal and structural changes are frequently associated with full-thickness supraspinatus tendon tears, particularly if the supraspinatus is significantly retracted. In this static MRI series, the data do not support the occurrence of classical subcoracoid impingement as an aetiology; however, they may support the possibility of a dynamic mechanism, to which future studies could be directed.
MacMahon
P J
PJ
Department of Radiology, Cappagh National Orthopaedic Hospital, Finglas, Dublin, Ireland. petermacmahon@yahoo.com
Taylor
D H
DH
Duke
D
D
Brennan
D D
DD
O'Brien
J
J
Eustace
S J
SJ
D000174:Acromion / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006811:Humerus / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000473:pathology; D000070636:Rotator Cuff Injuries; D019534:Shoulder Impingement Syndrome / Q000473:pathology; D012785:Shoulder Joint / Q000473:pathology; D013708:Tendon Injuries / Q000473:pathology*; D013710:Tendons / Q000473:pathology