ABSTRACT
PURPOSE: The effects of local injection of TGF-beta1 on the normal patellar tendon and the characteristics of remaining tendon after the partial resection of hypertrophic one were investigated. MATERIALS AND METHODS: TGF-beta1 was injected into the right patellar tendon of mature rats weekly for 3 weeks. Histological study, biomechanical analysis and the transmission electron microscopic evaluation were done. Half of hypertrophic tendon was resected at 4 weeks after the last injection and the same analyses were RESULTS: TGF-beta1 treated tendon increased in cross sectional area but decreased significantly in maximum tensile stress. The hypertrophic tissue was mainly composed of small collagen fibrils. After the partial resection of hypertrophic tendon, there was no significant difference in maximum tensile stress between remaining and control tendons. There were relatively larger collagen fibrils in the remaining tendon tissue than in non-resected hypertrophic one. CONCLUSION: Local injection of TGF-beta1 induced the hypertrophy of normal tendon. After the partial resection of hypertrophic tendon, the remaining one showed the more similar biomechanical properties to normal one.