Experimental study of ectopic activation about allograft segment tibia of rabbits / 中华显微外科杂志

ABSTRACT

Objective To compare of the difference about ectopic activation between autogenous bone graft and allograft from large segment tibia of rabbits.Methods Eighty healthy adult Chinese rabbits (6 months of age),weighing (2.5 ±-0.5)kg,were randomly divided into experimental group (allogeneic bone group) and the control group (autograft group),40 rabbits in each group.Another 10 rabbits were allogeneic bone donor.In experimental group,when 1.5 cm long rabbit tibial allograft were finishied,they were implanted into spatium intermusculare between the musculus rectus femoris and medial vastus muscle of the rabbit around the saphenous artery and were fastened to the femur by 1.0 mm Kirschner-wire.In control group,autologous tibias were done,the same as experimental group including length and position and method.Four weeks and 8 weeks and 12 weeks postoperative,respectively,the postmortem specimens were examined gross and immunohistochemistry and the expression of BMP-2 and collagen type Ⅰ of transplanted bone tissue were detected.Results BMP-2 mainly exist in cytoplasm of osteoblasts and chondrocytes undifferentiated mesenchymal cells.Collagen type Ⅰ primarily exist in the bone matrix around the pit of bone.The expression level of BMP-2 of experimental group in postoperative 4,8,12 and 16 weeks were 85.25 ± 4.47,109.44 ± 14.69,141.85 ± 9.45,116.25 ± 14.18,respectively,and the expression level of BMP-2 of control group were 103.78 ±-6.59,124.95 ± 14.94,145.46 ± 8.10,112.48 ± 13.27,respectively.The expression level of collagen type Ⅰ of experimental group in postoperative 4,8,12 and 16 weeks were 78.74 ± 7.99,95.95 ± 6.99,139.91 ± 4.32,137.76 ± 3.48,respectively,and the expression level of BMP-2 of control group were 88.87 ± 11.26,102.45 ± 2.82,140.76 ± 4.62,139.05 ± 4.55.Compared with control group,there was a significant difference in the expression level of the BMP-2 and collagen type Ⅰ of experimental group in postoperative 4,8 weeks (P ＜ 0.05),but,there was no significant difference in the expression level of the BMP-2 and collagen type Ⅰ of experimental group in postoperative 12,16 weeks (P ＞ 0.05).The amount increased gradually during 4 weeks,8 weeks,12weeks,peaked at 12 weeks,BMP-2 displayed a downward trend at 16 weeks,and collagen type Ⅰ basiclly maintain the level of 12 weeks.Conclusion Allograft segment could complete activation while they are implanted into spatium intermusculare containing famous blood supply within 3 months,there is no significant difference between autologous bone and allograft,it shows the feasibility of ectopic activation about allograft segment.