| Lumbar intervertebral disc protrusion is commonly seen in the orthopedic practice. Now the surgical procedures for it have been adopted more and more with the people's high expectancy of life quality and doctors' enhanced knowledge. The aim of resection in the operation is to remove the degenerative discs as much as possible and to decompress the nerve roots, which ensures the short-term effective clinical results. It is a problem worth considering to maintain lumber stability on the basis of adequate decompression. This experiment is to study the change in lumber stability after graded facetectomy from the biomechanical point of view and to provide the experimental data and theoretical basis, which are to be identified in clinical practice.1. The biomechanical research on the effect of graded facetectomy in lumber intervertebral disc protrusion on lumber stability: Objective: To simulate the removal of the apophyseal processes and intervertebral discs in lumbar disc protrusion operation in relation to lumbar stability. Method: The lumbo-sacral specimens from eight fresh cadavers were biomechanically analyzed in flexion, extension, left and right lateral bending positions under different loads of 100N-300N. Different conditions of stability were observed after discectomy and L4~5 graded facetectomy. Results: The procedures of unilateral semi-laminectomy with semifacetectomy in the normal subjects was significantly different from those without operation in biomechanical properties, such as strain, stress intensity, ROM and horizontal displacement (p<0.05). Unilateral fenestration+resection of a half of the apophyseal processes in the simulated lumbar disc protrusion was significantly different from the uninjuried subjects in biomechanical properties (p<0.05). Excessive facetectomy was likely to cause lumbarinstability. The normal samples were significantly different from those with the resected degenerated discs biomechanically (p<0.05). Conclusion: We hold that the damage to the posterior structures should be minimized on the basis of sufficient decompression in order to maintain or rebuild lumbar stability. The extent of resection of the processes should be limited to the decompression of the lateral recess in the treatment of lumbar disc protrusion and facetectomy of more than a half of the processes is likely to cause lumbar instability.2.The clinical research on the effect of graded facetectomy in lumber intervertebral disc protrusion on lumber stability: Objective: To study the effect of graded resection of the apophyseal joints all in addition to discectomy on lumbar stability in lumbar intervertebral disc protrusion. Method: 89 cases of lumbar intervertebral disc protrusion were classified into fenestration, fenestration + facetectomy less than a half of the processes, fenestration + facetectomy equal to or more than a half of the processes, semilaminectomy and panlaminectomy groups all in addition to discectomy. The postoperative follow-ups (according to JOA evaluation scores) and pre- and post-operative hyperextension and hyperflexion X-ray films were compared. Results: The improvement rate in JOA score in the groups of fenestration and fenestration with facetectomy less than a half of the processes were higher than the groups of facetectomy equal to or more than a half of the processes, semilaminectomy and panlaminectomy and there was a significant difference (p<0.05) in terms of the above-mentioned parameters. The long-term clinical result was worse in the groups of facetectomy of more than a half of the processes, semilaminectomy and panlaminectomy and the incidence of clinical instability was high in the groups. Lumbar instability occurred mostly in medio- and long-term follow-ups. Conclusion: The destruction of the discs and facet joints play an important role postoperative lumbar stability. Facetectomy less than a half of the processes maintains lumbar stability.Facetectomy equal to or more than a half of the processes may l...
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