[Experimental research of allogeneic bone sheet in preventing epidural adhesion]

To study the effect of the allogeneic bone sheet that has been treated by the freeze-drying and radiation sterilization in preventing the epidural adhesion after laminectomy in sheep.

Laminectomy was performed on L(3,4) and L(1,5) of 12 adult male sheep. After operation, one site of L(3,4) or was covered by the allogeneic bone sheet in "H" shape after the freeze-drying and radiation sterilization treatment; and the other site was used as a control. The sheep were killed and the specimens were retrieved at 4, 8, 12, 16, 20 and 24 weeks after operation to observe the scar formation process. X-ray and CT scan were performed in the segments of L(3,4) and L(4,5) at 4 and 24 weeks.

Four weeks after operation, the position and the shape of the allogeneic bone sheet were good in condition, and no lumbar spinal stenosis or compression of the dura was found in the experimental sections. Twenty-four weeks after operation the examination on the experimental sections revealed that the vertebral canal reconstruction was completed, the allograft was absorbed almost completely, and inoculation with the lamina of the vertebra and the shape of the lumbar spine were good, with no fibroid tissues found in the epidural area. Compared with the control segment, the dura adhesion degree in the laminoplasty segment was significantly decreased (P < 0.01), and the dura sac remained in a good shape. There was no obvious compression on the dura.

The allogeneic bone sheet after the treatment of freeze-drying and radiation sterilization can effectively reduce the scar formation after laminectomy and prevent postoperative recurrence of the spinal stenosis.