Aging of the rotator cuff.

The many years of challenge in treating athletes disabled by tendinitis stimulated a study of the aging of tendons. Autopsy specimens, representing tendons from 20-, 50-, and 70-year-old subjects, were obtained. Each specimen, consisting of a wedge of the greater tuberosity with the attached supraspinatus tendon, was examined roentgenographically to study the morphologic features of the greater tuberosity and was decalcified and stained with Safranin O to evaluate the amount of fibro-cartilage, with van Gieson to identify Sharpey's fibers, and with hematoxylin and eosin to determine cellularity, fiber integrity, and vascularity of the tendon. The comparison related to chronological age documented a morphologic change of the greater tuberosity and progressive degeneration of all elements of the tendinous structures with progressive (1) osteitis of the greater tuberosity, cystic degeneration, and irregularity of the cortical margin; (2) degenerative sulcus between the greater tuberosity and the articular surface; (3) disruption of the integrity of the attachment of the tendon to the bone by Sharpey's fibers; (4) loss of cellularity, loss of staining quality, and fragmentation of the tendon; (5) diminution of the vascularity of the tendon; and (6) diminution of fibrocartilage.