The Study of the Regeneration of Nucleus Pulposususing Nanofiber-based Scaffold : In Vitro and Animal Study / 대한정형외과학회잡지

PURPOSE: To investigate the potential of nucleus pulposus (NP) regeneration with a nanofiber-based scaffold inserted in the degenerative disc. MATERIALS AND METHODS: A nanofiber scaffold was fabricated using an electrospinning technique. In the in-vitro study, a total 18 discs with endplates on both sides were obtained from six New Zealand White (NZW) rabbits. A small volume of NP was removed through the hole from the endplate. The specimens were classified into three groups, intact (normal), inserting nanofiber scaffold (nanofiber), and defect (defect) group. The discs were analyzed by MRI scan and histological analysis. Six NZW rabbits were used in the in-vivo study. An annulotomy was performed through the dorsal approach L2-3 and L3-4 disc. A nanofibrous sheet type scaffold was inserted at L3-4. X-ray, MRI and histology analysis were carried out at 4, 8, 12 weeks after surgery. RESULTS: In the in-vitro study, the Nanofiber groups showed higher signal intensity and cell proliferation than the defect groups. In the in-vivo study, the Nanofiber and defect groups showed significant degeneration but there was no significant difference between these groups. CONCLUSION: Nanofiber scaffold might provide a favorable environment for regenerating disc cells. However, a defect in the annulus fibrosus (AF) might delay the regeneration of the disc cell at the nanofiber group. Therefore, NP regeneration using any scaffold should be examined along with AF regeneration for effective clinical applications.

Experimental Annulotomy-induced Degeneration in Rabbit Intervertebral Discs: Comparative Study Between Incomplete and Complete Annulotomy / 대한정형외과학회잡지

PURPOSE: To develop an animal disc degeneration model. MATERIALS AND METHODS: 12 female 8-month-old white New Zealand rabbits, weighing about 4-4.5 kg, were used. A retroperitoneal approach using a paravertebral incision was adopted. Using a number-11 blade, a transverse stab incision was made into the L3-4 and L5-6 disc through the antero-lateral annulus. At L3-4 level, complete annulotomy was performed and incomplete annulotomy at the L5-6 level. In the complete annulotomy group, extrusion of the nucleus after annulotomy was confirmed. Gross and histological findings, and lumbarx-rays and MRIs were analyzed. From simple x-rays, changes in disc heights were measured using NIH image software; degeneration grade was classified using MRI. RESULTS: The gross and histological findings showed progressive degenerative change in both groups, which were more severe in the complete annulotomy group. Simple radiographs showed a progressive decrease in the disc height and osteophyte formation in several samples, which were more severe in the complete annulotomy group. From the MRI findings, early degenerative findings were identified 2 and 3 months after complete and incomplete annulotomy, respectively. CONCLUSION: In conclusion, the disc degenerative process, following incomplete annulotomy, more resembled the natural course of disc degeneration than complete annulotomy.

Comparative Study of Disc Degeneration According to the Annulotomy Methodology: In Vivo Animal Study / 대한척추외과학회지

STUDY DESIGN: An in-vivo experiment. OBJECTIVES: To compare the results of various methodologies for an annulotomy, and evaluate the relationship between the degenerative change and the volume of an extruded nucleus according to the various methodologies. SUMMARY OF LITERATURE REVIEW: Many authors have reported that the traditional annulotomy technique is an open annulotomy. MATERIAL AND METHODS: 16 female white New Zealand rabbits, each weighing about 4-4.5 kg, were used. A retroperitoneal approach, using a paravertebral incision, was used. Using a number 11 blade, a 21G needle and a number 15 blade, transverse stab incisions, or puncture wounds, were made into the L3-4, L4-5 and L5-6 disc through the antero-lateral annulus. At all the experimental levels, a complete annulotomy, which confirms the leakage of nucleus pulposus after an annulotomy, was used. To check the extruded nucleus volume after each annulotomy, the gross findings and histological findings of 10 disc samples from each level were analyzed. Radiological methods were used simple lumbar x-ray and MRI. From simple x-rays, the change in the disc height was measured with NIH image software, and the degeneration grade was classified using MRI. RESULTS: The gross and histological findings showed the most advanced degeneration in the number 15 blade annulotomy group (L5-6 level), with the simple radiographs showing a fast decrease in the disc height. From the MRI findings, early degenerative findings were observed 2 months after the annulotomy in the number 11 and 15 blades groups. The largest extruded nucleus volume was observed in the number 15 blade annulotomy group. CONCLUSION: In conclusion, the degenerative change in the disc, following an annulotomy, was related to the volume of the extruded nucleus.