Clinical And Experimental Study On Secondary Changes Of Intervertebral Disc After Nucleoplasty

Objectives 1.To analyze the clinical efficacy and reasons for reoperation of nucleoplasty for lumbar disc herniation.2.To investigate the effects of nucleoplasty on the mobility of the surgical segment,disc strain and stress distribution.3.To investigate the secondary changes in imaging,histology and molecular biology of the intervertebral disc after nucleoplasty.4.To evaluate the effect of nucleoplasty combined with osteogenic protein-1 injection in delaying lumbar disc degeneration in rabbits.Methods 1.Summarize the patients with lumbar disc herniation who were hospitalized from 2015 to 2017 and divided into 77 cases in the conservative treatment group and 52 cases in the nucleoplasty group according to the treatment method.The VAS score of leg pain,pain relief rate,excellent and good rate(MacNab’s criterion)and Oswestry disability index were compared between the two groups.2.A three-dimensional finite element model of L4/5 disc herniation before and after nucleoplasty was constructed to analyze the surgical segment mobility in anterior flexion,posterior extension,left and right lateral flexion,left and right axial rotation,and the strain and stress distribution of the disc in neutral position before and after nucleoplasty.3.24 New Zealand rabbits with L3/4,L4/5 and L5/6 discs were randomly underwent untreated,full-thickness annulus puncture and nucleoplasty to analyze disc imaging,histological and molecular biological changes at 2,6 and 12 weeks postoperatively.4.8 New Zealand rabbits with L2/3 discs underwent nucleoplasty combined with osteogenic protein-1 injection(experimental group)and L4/5 discs underwent nucleoplasty only(control group)and were observed for disc height and MRI grading of disc degeneration at 2,6 and 12 weeks postoperatively.Results 1.The pain VAS scores and Oswestry disability index of patients in both the conservative treatment group and the nucleoplasty group at 1 month after discharge were significantly lower than those before treatment(P<0.05),and the pain relief rate and excellent and good rate in the nucleoplasty group were significantly higher than those in the conservative treatment group(P<0.05).In the final follow-up,the pain VAS scores and Oswestry disability index in the nucleoplasty group were significantly lower than those in the conservative treatment group(P<0.05).2.The finite element model showed an increase in surgical segment mobility of 0.19°to 0.96° after surgery compared with that before surgery,and an increase in axial rotational mobility of nearly 2°in the dynamic position.In the neutral position after surgery,the outer layer of the annulus fibrosus showed an increase in strain,with a maximum deformation increase of 0.01669 and a decrease in the maximum stress value of 0.012 MPa in the surgical disc.3.The height of the rabbit discs in both the nucleoplasty and puncture groups showed a progressively decrease over time(P<0.05)and a gradually increase in MRI grade of disc degeneration(P<0.05).Compared with the puncture group at the same time point,the MRI grade of the disc was significantly higher in the nucleoplasty group(P<0.05).The histological grading scores of the rabbit discs in the nucleoplasty and puncture groups gradually increased over time(P<0.05).Compared with the puncture group,the histological grading scores of the disc at all time points were significantly increased in the nucleoplasty group(P<0.05).The type I collagen staining of the disc nucleus pulposus cells in the nucleoplasty and puncture groups gradually deepened over time,and the type II collagen staining gradually decreased.4.The disc height in both the nucleoplasty combined with osteogenic protein-1 injection group and the nucleoplasty control group showed a progressively decrease over time,and the difference between the two groups was not significant.The MRI grade of disc degeneration gradually increased over time.The MRI grade of disc degeneration in the nucleoplasty combined with osteogenic protein-1 injection group was significantly lower than that in the nucleoplasty group at 12 weeks postoperatively(P<0.05).Conclusions 1.Lumbar disc herniation less than 5mm and intervertebral disc height above 50%is suitable for nucleoplasty treatment.The curative effect of nucleoplasty is better than that of conservative treatment for lumbar disc herniation with intact annulus fibrosus accompanied by increased intradiscal pressure.2.Finite element analysis shows that nucleoplasty increases the mobility of the surgical segment,affects the disc strain and stress distribution,and might accelerate disc degeneration.3.Both annulus fibrosus puncture injury and nucleoplasty can lead to disc degeneration in the surgical segment.On the basis of annulus fibrosus puncture injury,nucleoplasty can produce a cumulative efect of disc degeneration,thus leading to accelerated disc degeneration and increased degeneration in the surgical segment.4.Combination with osteogenic protein-1 injection might slightly delay intervertebral disc degeneration after nucleoplasty.