脊髓损伤对大鼠股骨骨密度与生物力学特性的影响

目的探讨脊髓损伤(spinal cord injury, SCI)对大鼠股骨生物力学和骨密度(bone mineral density, BMD)的影响. 方法将40只3月龄大鼠随机分为SCI组和对照组,SCI组于T10椎体处完全切断脊髓,对照组仅行椎板切除术.于术后3,6周分2批处死动物进行股骨骨密度和生物力学测定. 结果术后3周时SCI组大鼠股骨远端BMD较对照组显著下降(P<0.05);术后6周时SCI组股骨近端BMD与对照组比较,下降差异显著(P<0.05);股骨远端BMD较对照组下降差异非常显著(P<0.01);股骨干BMD与对照组相比有降低趋势,但无统计学意义.术后3周时股骨颈最大载荷、最大变形、结构刚度及能量吸收在2组间差异均无统计学意义.术后6周时最大变形、结构刚度和能量吸收均低于对照组(P均<0.05),最大载荷低于对照组,差异具有极显著性意义(P<0.01). 结论脊髓损伤后松质骨骨密度和生物力学性能的降低先于密质骨.脊髓损伤后6周时SCI组股骨松质骨的骨密度及生物力学参数均显著低于对照组,脊髓损伤后6周的大鼠可作为骨质疏松动物模型.

The effect of spinal cord injury on bone mineral density and biomechanical properties of the femur in rats

Objective To explore the effect of spina l cord injury(SCI) on the bone mineral density(BMD) and biomechanical properties o f femur in SD rats. Methods Forty 3-month-old rat s were randomly divided into the SCI group and control group with 20 in each gro up. Rats in the SCI group underwent spinal cord transection at the tenth thoraci c vertebrae. Rats in the control group underwent a sham procedure. Ten rats from each group were sacrificed at the time points of 3 weeks and 6 weeks after the operation, respectively. BMD measurement in different part of femur and test of biomechanical in femoral neck were performed. Results BMD of distal femur in SCI group was significantly lower than that in control group at 3 weeks postoperatively ( P <0.05).Significantly decreased BMD was d etected in proximal and distal femur in rats with SCI at 6 weeks in comparison w ith the controls ( P <0.05, P < 0.01 respectively). There was no signifi cant difference of the BMD in shaft of femur between the two groups at 3, 6 week s postoperatively. There was no difference in value of maximum load, maximum def ormation, energy absorption capacity and structural rigidity in femoral neck thr ough bending test at 3 weeks. However, there are significant decrease in value o f maximum load, maximum deformation, energy absorption capacity and structural r igidity in SCI group in comparison with the controls at 6 weeks( P <0.01, P <0.05, P <0.05, P <0.05, respectively). Conclusion Fall of BMD and decrease of biomechanical properties in cancellated bone is prior to that in compact bone in rats with SCI. Rats with SCI had a signific ant decrease of cancellated bone mass and biomechanical property of femoral head at 6 weeks after injury and it culd be used as the osteoporosis models followin g SCI.