Adjacent segment disease after anterior cervical interbody fusion / 中国矫形外科杂志

ABSTRACT

[Objective]The present study was undertaken to investigate the incidence of symptomatic adjacent segment disease after anterior cervical interbody fusion(ACIF),and to identify the factors which are related to the development of this disease.[Method]From 1981 to 1997,a total of 160 patients underwent anterior cervical in terbody fusion for intervertebral disc herniation and cervical spondylosis.A total of 112 patients were followed up clinically and radiologically for more than two years.Of them,74 were men and 38 were women,the average age at operation was 51 years(ranged,31~70 years).Of the 112 patients,66 had one,44 had two and 2 had three levels of fusion.Follow-up evaluation was primarily viaclinical visited.The post-operative course of any symptoms,the findings of neurological examination and serial follow-up radiographs were performed in all patients.The diagnosis of symptomatic adjacent segment disease was based on the presence of new radiculopathy or myelopathy symptoms referable to an adjacent level,and the presence of a compressive lesion at an adjacent level by magnetic resonance imaging or myelography.We evaluated the correlation between the incidence of symptomatic adjacent segment disease and the following clinical parameters(age at operation sex,number of the levels fused)and radiological parameters(preoperative cervical spine alignment,preoperative range of motion of C_(2~7) cervical spine,antero-posterior spinal canal diameter,preoperative existence of an adjacent segment degeneration on plain radiograph,myelography and magnetic resonance imaging(MRI).[Result]The average length of follow-up was 9.4 years(ranged,2 to 19 years).Symptomatic adjacent segment disease developed in 19 out of 112 patients(19%)followed.A Kaplan-Meier survival analysis was performed in order to follow the disease-free survival of the entire series of patients.The disease free survival rates were 89% at 5 years,84% at 10 years and 67% at 17 years.The incidences of indentation of dura matter on pre-operative myelography or disc protrusion on MRI at the adjacent level were significantly higher in disease cases(P=(0.0 087),(0.0 299),respectively;Chi-square test).Howerer,the other parameters did not show a statistically significant difference.There were 7 cases(37%)who had failure of non-operative treatment and additional operations were performed.[Conclusion]The incidence of symptomatic adjacent segment disease after ACIF was higher when pre-operative myelography or MRI revealed asymptomatic disc degeneration at that level regardless of the number of the level number fused,pre-operative alignment,spinal canal diameter of fusion alignment.