Risk Factor Analysis Of Non-fusion Segment Disease After Anterior Cervical Spondylosis Surgery

ObjectiveThe purpose of this study was to investigate the incidence and causes of non-fusion segment disease(NFSD),both adjacent and non-adjacent to a fused segment,after anterior cervical arthrodesis.MethodsBetween January 1998 and January 2011,two surgeons’ 171 patients who had an anterior cervical decompression and fusion were followed clinically for more than 5 years.The correlation between the incidence of symptomatic non-fusion segment disease and the following clinical parameters(age at operation,fusion levels,)and radiological parameters(number of patients who had a plate,anterior cervical decompression and fusion(ACDF)or corpectomy preoperative and postoperative cervical spine alignment,Pavlov’s ratio at the C5 level,and preoperative existence of a non-fusion segment degeneration on magnetic resonance imaging)was evaluated.ResultsA total of 16 patients in 171 patients had symptomatic non-fusion segmental disease,accounting for 9.36%.There were 12 cases of adjacent segment disease,the incidence was 7.02%,non-adjacent segment lesions in 4 cases,and the incidence was 2.34%.The follow up time was 1 to 13 years after surgery,an average of 5.2 years.General conditions:Patients with NFSD compared with patients without NFSD,there was no significant difference in age,sex,BMI(P> 0.05).The surgical approach: The difference between patients with NFSD and patients without NFSD surgery was not statistically significant(P> 0.05).The fusion segments: The number of fusion segments in patients with NFSD compared with those without NFSD was significantly different(P <0.05).The plate: NFSD patients and patients without NFSD in the number of plates compared,the difference was not statistically significant(P> 0.05).Preoperative cervical curvature: There was no significant difference in preoperative curvature of cervical vertebra between patients with NFSD and non-patients with preoperative NFSD(P> 0.05).Postoperative cervical curvature after operation: There was significant difference in postoperative cervical curvature(P <0.05).Cervical C5 level Pavlov ratio: There was no significant difference in C5 level Pavlov ratio between patients with NFSD and without NFSD(P> 0.05).The degree of disc degeneration: There was significant difference between the patients with and without NFSD in preoperative MRI disc degeneration(P <0.05).Multivariate logistic regression analysis: The risk factors associated with the occurrence of NFSD after anterior cervical fusion were as follows: degree of cervical curvature and disc degeneration after surgery.ConclusionsThe incidence of symptomatic non-fusion segment disease after anterior cervical arthrodesis has multifactorial causes.Postoperative cervical lordosis and disc degeneration in non-fusion segments were major factors in the incidence of NFSD.