Collagen type III in rotator cuff tears: An immunohistochemical study.

The presence and distribution of collagen type III, which represents newly formed fibers of early repair, were investigated in four surgically removed en bloc specimens of complete rotator cuff tears. The patients were two men and two women who ranged in age from 63 to 71 years. They had received preoperative, conservative treatment for a period varying from 3 months to 3 years. For the identification of the collagen immunohistochemical staining was performed by the peroxidase-antiperoxidase method with the use of monoclonal antibody against human collagen type III. Collagen type III was discernible throughout the tendon proper in all specimens. It often occurred in association with proliferating fibroblastic cells. Collagen type III was abundant only in the perivascular spaces of the much thickened bursal wall that extended over the margins of the tear. We concluded that the presence of collagen type III indicates the need for a continued attempt for repair at the site of the tear, including both bursal and tendinous tissues.