CELLULAR-SURVIVAL AND PROLIFERATION IN AUTOGENOUS FLEXOR TENDON CRAFTS

In order to investigate fibroblast survival and proliferation in autog enous flexor tendon grafts, hindlimb intrasynovial and extrasynovial d onor tendons were placed within the synovial sheaths of the medial and lateral forepaw digits of 21 dogs (42 tendons) and treated with contr olled early passive motion. Intravital histologic evaluations with con focal microscopy and biochemical determinations of total DNA content a nd DNA synthesis were carried out at 10 days, 3 weeks, and 6 weeks. In travital staining of the extrasynovial tendon grafts demonstrated vari able degrees of cellular necrosis at the earliest intervals followed b y cellular repopulation with fibroblasts and neovascularization from s urface vessels. In contrast, intrasynovial tendon grafts were populate d predominantly by viable cells at each interval, with occasional patc hes of cell necrosis and fibroblast ingrowth. Total DNA content and DN A synthesis values in the intrasynovial donor tendons were significant ly lower than those seen in the extrasynovial tendon grafts at each in terval. Extrasynovial tendons appear to act as scaffolds, undergoing e xtensive cellular death followed by a rapid repair response. Findings that intrasynovial tendon fibroblasts survive the tendon grafting proc ess suggest that the nutritional supplies and metabolic requirements o f intrasynovial and extrasynovial donor tendons differ largely.