Effect Of Adjacent Two Levels Segment ACDF And ACCF On Lower Adjacent Segment Degeneration

PURPOSE:To compare the clinical effects of Anterior Cervical Discectomy and Fusion（ACDF）and Anterior Cervical Corpectomy and Fusion（ACCF）for patients with adjacent two levels cervical spondylopathy and its effect on lower Adjacent Segment Degeneration（ASD）,and then explore relevant influencing factors.METHODS:This study collected data from patients who underwent adjacent two levels ACDF or ACCF in China-Japan Union Hospital of Jilin University from January 2017 to December 2018.According to the inclusion and exclusion criteria,we had selected 78patients from 96 patients for inclusion in this study,including 41 males and 37 females.The age of cases between 30 and 79 years,had an average age of 52.04±9.77 years,follow-up time was 11-40 months,and the average was 15.73±4.16 months.Record the subject’s age,sex,occupation,body mass index（BMI）,smoking history,alcohol consumption history,hypertension history,symptom duration,surgical method,surgical segment,intraoperative blood loss,operation duration,length of stay,follow-up duration and the Japanese Orthopaedic Association（JOA）score,visual analogue score（VAS）,neck disability index（NDI）score and Oswestry disability index（ODI）score.In terms of imaging,angle indicators include C_2-7 Cobb angle,T1 tilt angle（T₁S）;the length indicators include the height of the lower adjacent intervertebral disc,the height of the fusion segment and the C_2-7 sagittal vertical distance(C_2-7 SVA);finally,the degeneration of the lower adjacent vertebral segment was evaluated according to the ASD diagnostic criteria.RESULTS:Patients were divided into ACDF group and ACCF group according to the operation method,regarding general conditions,no significant differences were found between the two groups（P>0.05）.At the last follow-up,the unfused bone graft did not occur.There were 19 patients（24.4%）with ASD in 78 patients,including 9 patients（23.1%）with ASD in ACDF group and 10 patients（25.6%）with ASD in ACCF group,there was no statistical difference in surgical procedure（P>0.05）.Operation duration and intraoperative blood loss were significantly less in ACDF,and C_2-7 Cobb Angle was recovered well in one year after ACDF,we also found that ACDF maintains fusion segment height well,with statistically significant difference（P<0.05）.In terms of imaging indicators,there was no significant difference in the height of the lower adjacent disc,C_2-7 SVA,and T₁S angle between the two groups（P>0.05）.In terms of clinical efficacy,JOA score,NDI score,ODI score,VAS score,and the improvement rates of JOA score at 1 year after operation between the two groups were not statistically different（P>0.05）.The patients were divided into ASD group and non-ASD group according to degeneration,among which 9 patients（47.4%）received ACDF and 10patients（52.6%）received ACCF in the ASD group,and there was no statistical difference in operative methods compared with the non-ASD group（P>0.05）.In ASD group,this study found that age,the degree of lower adjacent intervertebral disc height loss,JOA score and NDI score had significant differences（P<0.05）.In terms of sex,occupation,BMI,smoking history,alcohol consumption history,hypertension history,symptom duration,length of stay,operation duration,intraoperative blood loss,fusion segment height,C_2-7 Cobb Angle,C_2-7 SVA,T₁S Angle,VAS score,ODI score and Improvement rate of JOA score at 1 year after operation,this study also did not find statistically significant differences between the two groups（P>0.05）.Finally,this study did Logistic regression analysis of the data,and the results suggested that age and preoperative JOA score are correlated with the occurrence of ASD（P<0.05）.CONCLUSION:ACDF had obvious advantages over ACCF in intraoperative blood loss,operation duration,maintenance of postoperative cervical spine height and curvature.In terms of the incidence of ASD and clinical efficacy,this study did not find significant difference between ACDF and ACCF.The risk factors for ASD included age,lower adjacent disc height,JOA score and NDI score,among which age was positively correlated with the occurrence of ASD and preoperative JOA score was negatively correlated with the occurrence of ASD.