Percutaneous Reinsertion of the Nucleus Pulposus

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 or 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 apparent 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.