绝对稳定固定对骨量减少长骨骨折愈合影响的实验研究*

目的探讨骨折端加压螺钉对兔骨量减少股骨骨折愈合的影响。方法 36只新西兰雌兔中随机选取30只肌注甲强龙构建骨量减少模型（包括模型组6只），另外6只为对照组（肌注生理盐水）。肌注后4周，模型组和对照组行骨密度，血清P1NP、CTX，Micro-CT检测。造模成功后，24只骨量减少兔建立股骨骨折模型，分为S1组（单纯钉板系统，4周）、L1组（骨折端加压螺钉结合锁定钢板，4周）、S2组（单纯钉板系统，8周）和L2组（骨折端加压螺钉结合锁定钢板，8周），每组6只。骨折术后4、8周行X线、Micro-CT、生物力学测试、组织病理及免疫组化分析。结果肌注后4 周，模型组腰椎骨密度为（216±21）mg/cm2，对照组为（251±21）mg/cm2；模型组股骨近端骨密度为（237±30）mg/cm2，对照组为（281±28）mg/cm2。与对照组比较，模型组P1NP及CTX均有提高（P＜0.05）。模型组腰椎三维骨密度为（208.61±18.75）mg/cm3，对照组为（243.83±21.17）mg/cm3。模型组的骨体积分数、骨小梁厚度及骨小梁数量较对照组下降，骨小梁分离度及结构模型指数较对照组上升（P＜0.05）。骨折术后X线示L1、L2组骨折愈合较快，S2组有1例出现骨折延迟愈合。术后4周，Micro-CT提示L1组骨痂组织的骨体积分数更高，骨小梁厚度明显、数量较多、分离度更低（P＜0.05）；L1组最大载荷及弹性模量更高（P＜0.05）；HE、Masson及番红固绿染色显示L1、L2组更早出现成熟骨组织；TRAP染色显示L1、L2组破骨细胞数量更少（P＜0.05）；免疫组化提示两组BMP-2 表达比较差异无统计学意义（P＞0.05）。结论在治疗骨量减少性长骨骨折时，骨折端加压螺钉结合锁定钢板固定有助于早期形成骨痂以及骨折的快速愈合。

英文摘要:

Objective To investigate the influence of interfragmentary lag screw on the healing of osteopenic femoral fracture in rabbits. Methods Thirty-six female white rabbits were randomly selected for i. m. injections of methylprednisolone sodium succinate (MPS) to make osteopenic model (n=30), including MPS group (n=6), or i. m. injections of equivalent normal saline (control group, n=6). After intramuscular injection for 4 weeks, BMD, serum level of P1NP and CTX, and micro-CT of MPS and control group were detected. Twenty-four osteopenic rabbits were randomly divided into. S1 group (without lag screw, 4 weeks), L1 group (locking plate combined with interfragmentary lag screw, 4 weeks), S2 group (without lag screw, 8 weeks), and L2 group (locking plate combined with interfragmentary lag screw, 8 weeks), six rabbits were in each group. X-ray, micro-CT, biomechanical test, histopathological and immunohistochemical changes were measured at 4 and 8 weeks postoperatively. Results After intramuscular injection for 4 weeks, BMD of lumbar spine in MPS group was (216±21) mg/cm2, which was (251±21) mg/cm2 in control group. BMD of proximal femur in MPS group was (237±30) mg/cm2, and that of control group was (281±28) mg/cm2. P1NP and CTX in MPS group were higher than those in control group (P<0.05). The three-dimensional BMD of lumbar spine in MPS group was (208.61± 18.75) mg/cm3, and that of control group was (243.83±21.17) mg/cm3. The bone microstructure parameters showed that the volume/total volume, trabecular thickness and trabecular number were significantly decreased in MPS group; trabecular separation and structural model index were increased in MPS group (P<0.05). X-ray showed that the fracture healing was faster in L1 and L2 group, and one developed delayed fracture healing in S2 group. Four weeks after operation, Micro-CT displayed that bone volume/total volume, trabecular thickness and trabecular number in L1 group were higher, and trabecular separation was lower; the maximum load and elastic modulus of L1 group were higher; HE, Masson, and safranin and fast green staining demonstrated that mature bone tissue appeared earlier in L1 and L2 group; TRAP staining exhibited that the number of osteoclasts was less in L1 and L2 group (P<0.05). Immunohistochemistry showed that there was no significant difference in BMP-2 between the two groups (P>0.05). Conclusion In the treatment of long bone fractures with osteopenia, locking plate combined with interfragmentary lag screw can achieve compression effectively, which is conducive to the early formation of callus and rapid fracture healing.

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