Effects Of The Ratio Of Autologous Bone Graft Area In TLIF On The Fusion Rate

Objective:The overarching goal of our research was to investigate different autologous bone graft area ratios in transforaminal lumbar interbody fusion（TLIF）and to evaluate the effects on the one-year interbody fusion rate satisfaction and clinical outcomes to determine the optimal range of autologous bone graft area and the volume needed.Methods:To study the clinical and imaging data of 57 patients who underwent single-level TLIF surgery in China-japan Union Hospital of Jilin University from January 1,2017to February 29,2021.According to the ratio（Sa/Se）of the average autologous bone graft area（Sa）to the average endplate area（Se）,the subjects included in the study were divided into three groups:A,B,and C:Group A:Sa/Se<19%;Group B:19%≤Sa/Se≤25%;Group C:Sa/Se>25%.A retrospective study was conducted on the general basic conditions,clinical efficacy scores,intervertebral space height,average endplate area,cage height,intervertebral fusion rate in each group.Statistical methods such as analysis of variance（single factor）,paired T test,nonparametric test,and chi-square test were used for data analysis.Results:The fusion rates of the three groups at 6 months after surgery,the fusion rates of the subjects in the B and C groups were significantly better than those in the group A（P<0.05）.The fusion rates of the three groups were significantly increased at 1 year after surgery compared with that at 6 months after surgery,and there was no statistical difference in the fusion rates between the groups（P>0.05）.The postoperative and final intervertebral space heights of the three groups were significantly improved compared with those before operation(P_all<0.05).There was no significant difference in the height of the intervertebral space between the three groups before and after the operation(P_all>0.05).However,there was a significant difference in the height of the final intervertebral space between the two groups B and C and the group A（P<0.05）.There were no significant differences in the general basic conditions（age,gender,surgical segment,etc.）,average endplate area and height of the cage used among the three groups(P_all>0.05).In terms of clinical efficacy scores,the postoperative and final VAS and JOA scores of the three groups of subjects were significantly improved compared with those before surgery（P<0.05）.There were no significant differences in VAS,JOA score and JOA improvement rate between groups A,B and C at preoperative,postoperative and finaloperative（P>0.05）.Concluision:In TLIF,the combination of interbody fusion device implantation and interbody autologous bone graft with extra bone grafting can provide better maintenance of intervertebral height in the early stage and alleviate the delayed bone union or bone delay caused by autologous bone resorption during early bone fusion,and can also promote intervertebral bone fusion to a certain extent.In this study,higher fusion rate and better clinical prognosis were achieved when the area ratio of intervertebral autologous bone graft was more than 19%.However,when the area ratio of intervertebral autologous bone graft was more than 25%,there was no significant increase in the increase of fusion rate,and excessive intervertebral graft may cause bone graft displacement.Excessive intervertebral bone grafting may cause displacement of the grafted bone.After further conversion of the bone graft volume in the study,we were able to conclude that the required intraoperative bone graft volume ranged from 2.9ml to 4.3ml.