Purpose: Surgical treatment for odontoid fractures is widely performed in practice. However, the choice of different surgical procedures remains controversial. Regardless of the surgical technique, the fusion situation is one of the important factors that affect the clinical efficacy. A discrepancy in fusion rate between the anterior odontoid screw fixation approach and the posterior C1-C2 arthrodesis approach has been suggested in clinical research, yet no consensus has been reached. This meta-analysis aims to synthesize the currently available evidence on the topic.
Methods: Most published comparative studies have limited statistical power to reach a solid conclusion due to the sample size constraint. In this condensed meta-analysis, we focused on the analysis of the reported fusion rates among selected comparative studies. The targeted comparative study design was chosen to control for potential confounding factors. However, the inclusion criteria of comparative studies limited our sample size and we were not able to obtain statistically meaningful sample size for other endpoints. On the other hand, fusion rate serves as an important clinical outcome and is the most commonly reported one from odontoid fracture studies.
Results: Results show that the overall fusion rate is lower in anterior group than in posterior group in both fixed effect model (RR = 0.90, 95 % CI 0.82-0.99) and random effect model (RR = 0.90, 95 % CI 0.83-0.97). There was no significant heterogeneity between these studies (p value = 0.5718), and no evident publication bias was detected by the Egger's test (t = -0.3541, df = 6, p value = 0.7354) and funnel plots. In general, age is not statistically associated with the choice of surgical approach (χ(2) = 0.29, df = 1, p value = 0.59) but appears to affect the clinical efficacy. The protective effect of posterior C1-C2 arthrodesis treatment on fusion remains significant in the elderly (≥60 years), but loses its significance in the younger age population (<60 years).
Conclusions: In light of these findings, we concluded that significant higher fusion rates were observed in patients who underwent posterior C1-C2 arthrodesis surgeries compared to those treated with anterior odontoid screw fixation.