| Abstract:Objective:Imitating the antieror approach operation for thoracolumbar fracture, to perform the subtotal resection of vertebral body and titanium rete autograft bone supporting, and the internal fixation through anterior screw-rods system and screw-plate system respectively. To compare the effect of both fixations on the blood flow in spinal segmental arteries after mehtylene blue injection, providing the theoretical basis for choosing the better internal fixator to protect the blood vessels in clinical treatment of thoracolumbar fracture by anterior approach operation. Methods:In this trial,16 samples from fresh swan thoracolumbar vertebrae with no spinal disorders were chosen and made into 16 trial subjects of T11-L1 FSU, kept 6cm or so bilateral segmental blood vessels and the surrounding soft tissues; meanwhile, ligament, joint capsule, and bone structure were kept intact. The samples were randomly divided into two groups with 8 in each, in which the standard anterior approach short segmental internal fixation was performed (fixed one injured vertebra, two adjoining intervertebral discs, and two adjoining vertebrae). Group A was performed T13 subtotal resction and titanium rete autograft bone supporting through anterior approach, fixed by screw-rods system; group B was performed T13 subtotal resection and titanium rete autograft bone supporting through anterior approach, fixed by screw-plate system. Assumed T13 as the injured vertebra, it was first fixed with the adjoining vertebra (T12 and T14) in both groups. The left side of the vertebra was then operated on and the segmental blood vessels of vertebra surface were ligated in both groups, with the vessels of the fixed vertebrae remained. Before the operation, the normal saline with 20IU/ml heparin sodium was injected into the beginning of bilateral segmental vessels from T12-T14 respectively. The subtotal resection of T13 vertebra by anterior approach and titanium rete autograft bone supporting were made, followed by T12-T14 screw-rods system and screw-plate system internal fixations respectively. Again, the normal saline with 20IU/ml heparin sodium was injected into bilateral segmental arteries from T12-T14. Soon after, the methylene blue was injected into the beginning of bilateral segmental arteries from T12-T14 at 0.2ml/s, until the methylene blue spilled out of the cut end far from the heart of the segmental arteries, or the manometer catch of the injector swaying. The perfusion capacity of methylene blue was then recorded. The data from operated and contralateral in one plane were processed as paired sample; whereas the data from the operated sides in both groups as independent sample. The t-test of that were all made by SPSS 14.0 software, the distinction is considered had statistical significance when P<0.05. Results:(1) Comparison between the operated side and contralateral of T12 in group A:the methylene blue perfusion capacity of the operated side was 30%-71% of that of contralateral, averaged 55%,statistically significant(P<0.05); (2) comparison between the operated side and contralateral in group B:the methylene blue perfusion capacity of the operated side was 70%-88% of that of contralateral,averaged 80%, statistically significant (P<0.05); (3) comparison of bilateral sides of T13 from all samples in both groups before operation:the methylene blue perfusion capacity of the operated side was 1.00625ml, the contralateral 1.00ml, P>0.05, no statistically significance.(4) comparison of bilateral sides of T13 from all samples in both groups after operation:the methylene blue perfusion capacity of the operated side was 0.26875ml, the contralateral 1.00ml, P>0.05, statistically significant. (5) Comparison between the operated side and contralateral of T14 in group A:the methylene blue perfusion capacity of the operated side was 53%-71% of that of contralateral, averaged 57%, statistically significant (P<0.05); (6) Comparison between the operated side and contralateral of T14 in group B:the methylene blue perfusion capacity of the operated side was 77%～93% of that of contralateral., averaged 85%, statistically significant (P<0.05); (7) Comparison of the operated sides between group A and B in T12: the average value of methylene blue perfusion capacity was 0.5375ml in group A and 0.7375ml in group B; Obtained by t-test, P=0.019, P<0.05, statistically significant. (8) Comparison of the operated sides between group A and B in T14: the average value of methylene blue perfusion capacity was 0.725ml in group A and 1.1125ml in group B; Obtained by t-test, P=0.019, P<0.05, statistically significant. Conclusion:Both screw-rods and screw-plate systems in anterior approach operation lead to instant compression of the segmental blood vessels. However, different severity of compression (P<0.05) on the segmental vessels, as well as to vessels in different segment(T12 and T14)present by using different internal fixator. The screw-rods system leads to less severe compression on the unligated segmental vessels of the fixed vertebra, providing a better protection to the segmental blood vessels. The fact that even though both of the two systems affect the instant flow in the segmental blood vessels, the screw-rods system does lead to less injury, now provides the theoretical basis for choosing the better internal fixator to protect the blood vessels in clinical treatment of thoracolumbar fracture by anterior approach operation. |
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