Collagen biosynthesis in rabbit intraarticular patellar tendon transplants

Autogenous patellar tendon grafts were transplanted into the knees of 40 New Zealand White adult rabbits. Grafts were subsequently analyzed for rate of collagen synthesis, collagen content, collagen type, histologic change, and cyanogen bromide cleavage patterns of collagen to closely assess the nature of collagen in tendon grafts up to 2 years from the time of transplan tation. Tendon grafts were placed in rabbit knees as free fragments or were attached to synovium. These studies show that tendon grafts, even without vascularization or stress, remain viable after intraartic ular transfer. Vascularization produces a trend toward increased collagen synthesis, but statistical analysis suggests that control levels of collagen synthesis con tinue after tendon transfers into rabbit knees. Cyanogen bromide cleavage peptides showed appropriate colla gen formed by unstressed autogenous tendon trans plants removed from rabbit knees up to 2 years from transplantation. All tendon grafts degenerated initially, but began to form histologically healthy looking con nective tissue by 18 to 24 weeks after transplantation. Overall, the results are encouraging with regard to the fate of intraarticular tendon grafts.