Introduction: Pseudarthrosis after multilevel posterior cervical or cervical‐thoracic fusions is a common complication. We investigated the effect of pseudarthrosis on cervical aligment. Futhermore, we report the effect of type of bone grafts on the rate of pseudarthrosis in patients undergoing multilevel posterior cervical or cervical‐thoracic fusions.
Methods: We assembled a multicenter (4 sites) radiographic and clinical database of patients that had undergone 3 or more level posterior cervical or cervical‐thoracic fusions for degenerative disease from January 2008 to May 2013 with at least 2 years of post‐operative (post‐op) follow‐up. Patients were divided into two groups: group I (fusion ending in the cervical spine) and group II (fusion extending into the thoracic spine). All radiographic measurements were performed by an independent experienced clinical researcher. For the analysis, bone grafts were divided into four groups: local only; local and allografts; bone morphogenetic protein (BMP) only; and iliac crest only. Current smokers included those patients smoking at the time of or within 6 months of their surgery. Paired t‐test was used to compare means. Analysis of variance (ANOVA) was used to investigate the effects of type of bone grafts on the rate of pseudarthrosis. Level of significance was set at α = 0.05.
Results: Rate of pseudarthrosis in group I and group II were 21.2% and 10.96%, respectively. Mean age of patients with pseudarthrosis in group I and group II were 56( ± 9) and 67 ( ± 4) years, respectively. Females had higher numbers of pseudarthrosis than males (group I: 67% vs. 33%; group II: 55% vs. 45%; p < 0.05). Overall, 53.3% of the patients with pseudarthrosis were current smokers. The rate of smoking in the solid fusion group was 21.9%. The odds ratio of pseudarthrosis for a smoker compared with a non‐smoker was 4.071 (95% CI: 1.798 ‐ 9.221). Mean number of spinal levels treated for patients with pseudarthrosis in group I and group II were 3.6( ± 0.79) and 6.2( ± 2.5), respectively. Mean T1 slope for patients with pseudarthrosis increased significantly (2 wk vs. 2 year post‐op) in both groups (p < 0.05). Both groups with pseudarthrosis had significantly higher mean C2‐C7 sagittal plumbline at 2 years follow‐up (p < 0.05). Mean cervical lordosis decreased in both groups with pseudarthrosis (2 wk vs. 2 year post‐op). The difference was not statistically significant (p > 0.05). Overall, ANOVA showed no significant effect of type of bone grafts on the rate of pseudarthrosis (p > 0.05).
Conclusion: We conclude that pseudarthrosis affects cervical alignment in patients undergoing multilevel posterior cervical or cervical‐thoracic fusions. The study did not find any significant effect of type of bone grafts on the rate of pseudarthrosis. Prospective studies with additional patients and greater statistical power are needed to further understand the implications of pseudarthrosis on cervical alignment.