AUTOGENOUS FLEXOR TENDON GRAFTS - FIBROBLAST ACTIVITY AND MATRIX REMODELING IN DOGS

To investigate rates of cellular proliferation and matrix turnover in autogenous flexor tendon grafts, hindlimb intrasynovial (flexor digito rum profundus) and extrasynovial (peroneus longus) tendons were placed within the synovial sheaths of the medial and lateral forepaw digits of 18 dogs and treated with controlled early passive motion. After the dogs had been killed, short-term culture and labeling in vitro were u tilized to determine rates of DNA, proteoglycan, collagen, and noncoll agen protein synthesis. Schiff base covalent collagen crosslink concen trations and total collagen and protein content also were evaluated at intervals through 6 weeks. Tendon grafts of extrasynovial origin show ed greater rates of DNA synthesis and significantly elevated levels of proteoglycan, collagen, and noncollagen protein synthesis and Schiff base covalent collagen crosslink concentrations (dihydroxylysinonorleu cine) compared with intrasynovial tendon grafts. It was not clear to w hat extent the increased activity in the extrasynovial graft was due t o actual differences between the intrasynovial and extrasynovial tendo ns or to the responses of the connective tissue surrounding the extras ynovial tendon graft. Since both types of grafts demonstrated similar unaltered levels of collagen and protein content over time, these data suggest greater rates of matrix turnover in tendon grafts of extrasyn ovial origin than in those of intrasynovial origin. Coupled with previ ous findings showing increased cellular proliferation in extrasynovial tendon grafts, these data indicate that the process of translation to an intrasynovial environment necessitates a more active process of so ft-tissue repair and remodeling when extrasynovial donor tendons are u sed.