Osteoinducibility of degradable poly-D and L-lactic acid cage

English Keywords:Histology  Osteoblast  Poly-D and L-lactic acid  Ｌumbar vertebra  Ｆusion

English Abstract:

  【Abstract】 Objective：To investigate in vivo osteoinducibility of degradable poly-D and L-lactic acid cage.Method：48 healthy 9-month Neijiang Pig were divided into experimental group and control group randomly with 24 animals　ｉｎ　each group .Experimental group received PDLLA cage and filling autograft implantation，while control group received autograft alone with the same size at L4/5.At 1，3，6，9，12 and 18 monthｓ respectively，the animals were sacrificed，and the surgical sites were harvested and tested histologically.Result：At 1 month after operation：fibrous tissue was not found at the edge of cage and filling bone，while a few cartilage cells were evidenced between cage and vertebra；3 month after operation：a lots of collagen fiber，fibrous tissue and cartilage tissue grew interactively on cage-vertebra and cage-bone interfaces，ａｎｄ　ｍatured bone trabeculae formed by cartilaginous ossification was seen and ｄｉｓａｒｒａｎｇｅｄ；6 month after operation：collagen fiber，small amount of fibrous tissue，cartilage cells and osteocytes still ｃｏｕｌｄ be seen，ａｎｄ　ｐart of cartilage tissue fell into ossification and calcification；9 month after operation：fusion could be seen in experimental group，and the edge between filling autograft and vertebra disappeared，collagen fiber and fibrous tissue still could be seen and chondrocyte evolved into osteocyte；12 month after operation，bony fusion had been accomplished basically in experimental group，collagen fiber and fibrous tissue still could be seen，while bony fusion was finished completely　ｉｎｃｏｎｔｒｏｌ　ｇｒｏｕｐ；18 month after operation：bony fusion had been accomplished in two groups which approached normal bone tissue.Conclusion：Degradable poly-D and L-lactic acid cage act as intracartilaginous ossification and fibrous ossification rather than ｉntramembranous ossification.