Comparison Of Adjacent Segment Degeneration Following Minimally Invasive Or Conventional Open Transforaminal Lumbar Interbody Fusion

Objective To compare the difference of adjacent segment degeneration(ASD)following minimally invasive or conventional open transforaminal lumbar interbody fusion.Methods According to the operate methods,115 cases with lumbar disc herniation at L4/5 level were divided into 2 groups,53 of which consitituted the open group were underwent transforaminal lumbar interbody fusion surgery(TLIF)and the others who made up the minimally invasive group underwent minimally invasive surgery transforaminal lumbar interbody fusion(MIS-TLIF).Pfirrmann score and intervertebral space were compared before and after surgery to assess degenerative changes of adjacent discs.Seo score system was used to evaluate the damage of facet joint.Visual analogue scale(VAS)and the Oswestry disability index(ODI)were applied to assess the clinical effects.Results All patients were followed up for 6~48 months(mean,25.6 months).The VAS and ODI at preoperation,3 days after operation in two groups were compared respectively,the differences among 2 time points had statistical significance(P<0.05).The VAS and ODI at 1 year after operation,there was no significant difference between two groups(P<0.05).Compared with the conventional open approach,less decrease of cross sectional area and less severe fatty degeneration of the multifidus muscle were observed in minimally invasive group,the difference with statistical significance(P <0.05).Compared to minimally invasive group,the facet joint injury of open group caused by the surgery was more serious.The difference is of statistica significance(P<0.05).The study suggests a correlation between ASD and the degeneration of multifidus muscle and facet joint(P<0.05).Conclusion Compared with the conventional open approach,the MIS-TLIF gives the multifidus muscle and facet joint much more production,and effectively reduced the incidence rate of ASD.