| OBJECTIVE:Posterior structure defect of vertebra, epidural scar adhesion and instability of vertebra were notorious complications of spine surgery due to trauma, tumour, spinal canal stenosis and disc herniation. These complications can lead to the lumbar or nerve radicular pain (Failed back surgery syndrome, FBSS), which is one of the problems confronting spinal surgery. This experiment implanted artificial vertebral lamina made from n-HA/PA66 into the defect of vertebral lamina, and evaluated its value in preventing postlaminectomy scar formation,the dura adherence in the spinal canal, the compression of cauda equina and nerve root as well as the reconstruction of vertebral integrality. METHODS:27 male dogs aged one year were classified randomly into three groups: the experimental group(13 dogs),the control group(9 dogs)and the normal group(5 dogs). The L5 laminectomy were performed on the experimental and the control group, and the L5 was reconstructed in the experimental group by implanting n-HA/PA66 composite material, meanwhile was left uncovered in the control group for comparison. The specimens were taken respectively in different times: the 4th, 8th, 16th, 24th week after surgery, and were examined by the methods of plain roentgenography, histology, scanning electron microscope. In the 24th week after the operation, MRI was made in the experimental and the control group, all the dogs in the experimental, control and normal group were undertaken the biomechanical test. Finally, the collected data was analyzed by way of SAS 6.12 software.RESULTS:(1)The electronic microscope and histology: In the experimental group, from the 4th week after surgery, the vasoganglion and osteoblast cell were observed to start growing; In the 8th week, the osteoblast cell masses increased obviously, and the formation of new bone trabecula was observed; In the 16th-24th week, the cartilage cell and lamellar bone were observed. In the 24th week, the artificial vertebral lamina was still in good shape, the dura was not pressed and the ejection reaction was not found. Meanwhile, in the control group, the scar and striated muscles grew into the laminae defect, resulting in pressing the dura mater and forming the broad adhesion of fibroid tissue. Compared with the control segment, the dura adhesion degree in the laminoplasty segment decreased significantly (p<0.01). (2) MRI:Compared with the control group, the artificial vertebral lamina did not show the incline and shift, the reconstructed segment after the laminoplasty recovered the integrality, and there was no obvious dura adhesion and compression of the spinal cord and nerve root. (3) Biomechanical testing in vitro: In the compression testing, the compression extension of vertebral specimen was observed under 40N load, and there was no statistical difference shown among the experimental, control and normal groups (p>0.05); In the torsion testing, there was also no significant difference shown in the three groups (p>0.05).CONCLUSION: The experimental results show that n-HA/PA66 composite material not only has the attribute of good biocompatibility and osteoconductibility, but also can effectively prevent the scar formation and adhesion, and the spinal stenosis after laminectomy. Furthermore, it is easy to operate in clinical setting and suitable for the use in irregular bone defect area. Therefore, n-HA/PA66 composite material is an ideal artificial lamina material. |
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