Related factors of adjacent segment degeneration after cervical fusion surgery

English Keywords:Cervical spine fusion  Adjacent segment degeneration  Related factors

English Abstract:

  【Abstract】 Objectives: To investigate the related factors of adjacent segment degeneration(ASD) after cervical fusion. Methods: 235 patients were retrospectively collected and analyzed , who underwent anterior cervical discectomy and fusion(ACDF) in our hospital from January 31, 2009 to January 31, 2011, including 126 males and 109 females. The age ranged from 33 to 70 years(mean 50.42 years). The follow-up time was from 5 to 7 years(mean, 65.32 months). Anterior cervical standard anterioposterior and lateral X-ray, MRI examination were performed before surgery, at 1 week after operation and at the final follow-up. The age, sex, the time of follow-up, fusion segment number and radiographic parameters in X-ray such as preoperative cervical spinal canal ratio, the arc chord distance of cervical spine before and after operation, plate to disc distance(PDD) were recorded. According to the X-ray Kellgren degeneration classification method and Miyazaki MRI intervertebral disc degeneration classification method, the patients were classified into non ASD group and ASD group. The differences between the two groups were compared by t-test and χ2-test, and the related influencing factors of ASD were analyzed by Logistic regression. Results: At last follow-up, 107 patients(45.53%) showed adjacent segment degeneration in the X-ray or MRI. In the ASD group, the average age was 53.47±6.33(39 to 70 years) years, the mean postoperative arc chord length was 5.58±2.34mm(0 to 10.30mm), 50 cases were with both upper and lower PDD＜5mm, 43 cases with upper or lower PDD＜5mm, 14 cases with both upper and lower PDD≥5mm. In the non ASD group, the average age was 47.56±5.39 (33 to 61 years) years, the mean postoperative arc chord length was 7.63±2.34mm(0.10 to 11.21mm), 39 cases were with both upper and lower PDD＜5mm, 62 cases with upper or lower PDD＜5mm, 27 cases with both upper and lower PDD≥5mm. Between the two groups, the differences of age, postoperative cervical arc chord distance and PDD were statistically significant(P＜0.05). Gender, fusion segment number, preoperative cervical arc chord distance, difference of the preoperative and postoperative arc chord distance, the cervical spinal canal ratio showed no statistical difference between the ASD and non ASD groups(P＞0.05). The results of Logistic regression analysis showed that age, postoperative cervical arc chord distance and PDD had significant correlations with the incidence of ASD after operation(P<0.05). Conclusions: The age, postoperative cervical arc chord distance and PDD are the risk factors of ASD after cervical fusion. Patients with older age at the time of surgery, worse recovery of cervical curvature, and PDD less than 5mm, are more likely to get ASD. Omong all, the influence of age on ASD is the greatest.