| Abstract Objective : The defects of articular cartilage are an all too commonly encountered medical problem in bone and joint surgely, which may be caused by trauma or evolve during the course of diseases such as osteoarthritis , osteochondritis and osteonecrosis . Articular cantilage has a limited capality to repair spontaneously after injury .The large defects at articular cartilage are often repaired by fibrocartilage rather than normal hyaline cartilage .The resulting fibrocartilage are different form hyaline cartilage either biochemically or biomechanically and it ultimately deteriorates. It generally was thought that there was no effective clinical treatment that could restore a damaged cartilage surface and prevent the normal sequelae of degenerative joint disease . Recently , there are many investigations to accelerate repairing of the defects of articular cartilage and improve the quality of repairing tissue. Especially,the study has received more attention,which growth factors can induced the differentiation and proliferation of the chondrocytes and biodegradable matrix used in tissue engineering. However , the study on the repair of frill-thickness defects of articular 4 cartilage with a composite of recombinant human bone morphogenetic protcin-2(rhBMP-2) and pluronic F- 127 has been paid little attention. The object of this study was to investigate the effect of a composite of rhBMP-2 and pluronic on the healing of frill-thickness defects of arricular cartilage so as to provide a new non-traumatic method for the treatment of articular cartilage defects, especially for extensive and irregular defects of articular cartilage The another objective of this study was to provide information for the choice of carriers used in cartilage tissue engineering. Methods: One Full-thickness articular cartilage defects of 3.5mm in diameter were created through the articular cartilage into bleeding subchondral bone in the center of the articular surface of patella-femur. A total of?7 healthy adult rabbits were randomly divided into three groups Pluronic-fihled group, rhBMP-2/.Pluronic-fihled group and the control group The animals were killed at 4, 8and 12 weeks postoperativel~,and the defects were examined grossly and microscopically .The sections were evaluated blindly with use of a histological grading scale made by Wakitani et al .The shape of condrocytes collagen and the degradable time of Pluronic in the defects were examined with screening eleetron microscopy (SEM). Results : The repairing process in rhBMP/Pluronic group was faster and better than that in plunonic group and control group .At four weeks , the new tissue filled the entire area of the defects .At eight and twelve weeks, the gross appearance of the defects was similar to that of normal cartilage around the defects .The hiotological appearance of the empty defects was identical to that of the normal articular cartilage. One or two gaps or discontinuities between the repair and the adjacent cartilage were rare .The mature hyline chondrocytes and tyge II collagen were found with screening electron microscopy (SEM) . In control group and pluronic-fihlal group,at four weeks,there is a dent on the surface of repair tissue . At eight and twelve weeks , the repair tissue was lack of plastic and 5 has an irregu... |
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