Biomechanical Study Of Low Temperature Bone Cement Perfusion Volume After Osteoporotic Vertebral Compression Fractures

[Objective] Under the concept of rapid rehabilitation,combined with theory and practice,through biomechanical research,to explore bone cement perfusion volume required for the treatment of vertebral fractures with low temperature polymethacrylate bone cement(PMMA bone cement)combined with bilateral percutaneous kyphoplasty(PKP)as the optimal configuration at present.[Methods] Eight adult sheep were selected and 50 vertebrae were finally obtained after screening T8-L2 vertebrae.Using Latin square design,and the amount of bone cement perfusion was measured as a percentage of vertebral volume after fracture,and the vertebrae were divided into the first stage(5%,10%,15%,20%)and the second stage(15%,16%,17%,18%,19%,20%).Osteoporotic compression fractures were created through experiments,and the initial strength and stiffness of the vertebral body and the height of the anterior edge of the vertebral body after the fracture were recorded,and the post-fracture volume of each vertebral body was accurately calculated by finite element technique.Different volumes of low-temperature PMMA bone cement(as a percentage of post-fracture vertebral body volume)combined with bilateral PKP were used to treat the first and second stage fractured vertebrae sequentially,and then recompressed to record the postoperative strength and stiffness of the vertebral body and the height of anterior edge of vertebral body after operation.[Results](1)There was no significant difference of all vertebrae before operation in preoperative height,width and depth,bone mineral density before and after decalcification,strength and stiffness(P>0.05).(2)In the first stage after operation,the vertebral body strength in 20% group was higher than that before operation,while that in 5%,10% and 15%groups was lower than that before operation(P<0.05).The difference was statistically significant(P<0.05).The vertebral stiffness of each group after operation was lower than that before operation(P<0.05).The height of the anterior edge of vertebral body in each group after operation was higher than that before operation(P<0.05).There was no significant difference in postoperative vertebral body strength,stiffness and anterior edge height between 20% and 15% groups(P>0.05),but there was significant difference between 20% and 10%,5% groups(P<0.05).There was significant difference in postoperative vertebral strength and stiffness between 15%and 10% and 5% groups(P<0.05).There was significant difference in the height of the anterior edge of vertebral body between 15% and 5% groups(P<0.05),but there was no significant difference between 15% and 10%groups and 10% and 5% groups(P>0.05).(3)In the second stage after operation,the vertebral body strength in 15%,16% and 17% groups was lower than that before operation,while that in 18%,19% and 20% groups was higher than that before operation(P<0.05).There was no significant difference in postoperative strength among the three groups(P>0.05),but there was no significant difference among 15%,16% and 17% groups(P>0.05).The postoperative strength of 18%,19% and 20% groups was higher than that of 15%,16% and 17% groups,but there was no significant difference compared with 16% and 17% groups(P>0.05).Compared with15% group,the difference was statistically significant(P<0.05).The stiffness of vertebral body in each group after operation was significantly lower than that before operation(P<0.05),and there was no significant difference in postoperative stiffness among groups(P>0.05).The height of anterior edge of vertebral body in each group after operation was significantly higher than that before operation(P<0.05),and there was no significant difference in the height of the anterior edge of the vertebral body among the groups after operation(P>0.05).(4)Bone cement leakage:in the first stage,4 vertebral bodies in 20% group had leakage.In the second stage,2 vertebral bodies in 17% group had leakage trend,3vertebral bodies in 18% group had leakage,3 vertebral bodies in 19%group had leakage,and 5 vertebral bodies in 20% group had leakage.[Conclusion] In a certain range,the recovery of the strength,stiffness and height of the fractured vertebral body is related to the bone cement perfusion volume.Under the premise of ensuring no leakage of bone cement,using 16% bone cement(accounting for the volume of the fractured vertebral body)combined with bilateral PKP,the biomechanics and height recovery of the fractured vertebral body is the best.