Paper 166: Histopathology of the Supraspinatus Tendon in Rotator Cuff Tears

Abstract

Causes of rotator cuff pathology are poorly understood. Macroscopically intact supraspinatus tendon may show profound light microscopy changes. Comparative laboratory study. Tendon samples were harvested from 88 individuals (49 men, 39 women; mean age: 58.2 years) who underwent arthroscopic repair of a rotator cuff tear, and from 5 male patients who died of cardiovascular events (mean age: 69.6 years). A full thickness supraspinatus tendon biopsy was harvested en bloc within the arthroscopically intact middle portion of the tendon. Using Haematoxylin and Eosin staining, slides were assessed twice by the same examiner using a semiquantitative grading scale assessing fiber structure and arrangement, rounding of the nuclei, regional variations in cellularity, increased vascularity, decreased collagen stainability and hyalinization. Intra-observer reliability of the subscore readings was calculated. The mean pathologic sum-score of ruptured tendons was significantly greater than the mean pathologic score of control tendons. Within each specific category of tendon abnormalities, the control and ruptured tendons were significantly different (chisquare test); all variables were significantly different. There was good agreement between the two readings. Nonruptured supraspinatus tendons, even at an advanced age, and ruptured supraspinatus tendons are clearly part of two distinct populations.