Percutaneous reinsertion of the nucleus pulposus - An experimental study

Study Design. An analysis of the histologic changes in intervertebral discs after percutaneous reinsertion of the nucleus pulposus in rats. Objective. To devise a way to delay further disc degeneration resulting from spinal deformity and the adverse effects of various treatments. Summary of Background Data. The role of the nucleus pulposus of the intervertebral disc described by many investigators has not been fully clarified. Methods. Disc herniation was induced in the tails of 112 Wistar rats, using a fixation device between the 5th and 8th coccygeal vertebrae. After percutaneous nucleotomy at coccygeal vertebrae 5-6 and 6-7, fresh nucleus pulposus, cryopreserved nucleus pulposus, or an;artificial substitute was inserted into the intervertebral disc at coccygeal vertebrae 5-6. Two, 4, or 8 weeks after reinsertion, disc sections from each coccygeal level were studied histopathologically. Results. In the groups with reinsertion of fresh cryopreserved nucleus pulposus, degenerative changes of the disc with the reinserted nucleus at coccygeal vertebrae 5-6 were milder than those of the disc without reinsertion at coccygeal vertebrae 6-7. However, no ap parent benefit from reinsertion was observed in the group with artificial substitutes. Conclusions. Early reinsertion of the nucleus pulposus (fresh or cryopreserved) delays degeneration of such disc materials as the anulus fibrosus, endplate, and remaining nucleus pulposus.