Outcomes following anterior odontoid screw versus posterior arthrodesis for odontoid fractures: a systematic review and meta-analysis.

Odontoid fractures can be managed surgically when indicated. The most common approaches are anterior dens screw (ADS) fixation and posterior C1-C2 arthrodesis (PA). Each approach has theoretical advantages, but the optimal surgical approach remains controversial. The goal in this study was to systematically review the literature and synthesize outcomes including fusion rates, technical failures, reoperation, and 30-day mortality associated with ADS versus PA for odontoid fractures. A systematic literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines by searching the PubMed, EMBASE, and Cochrane databases. A random-effects meta-analysis was performed and the I2 statistic was used to assess heterogeneity. In total, 22 studies comprising 963 patients (ADS 527, PA 436) were included. The average age of the patients ranged from 28 to 81.2 years across the included studies. The majority of the odontoid fractures were type II based on the Anderson-D'Alonzo classification. The ADS group was associated with statistically significantly lower odds to achieve bony fusion at last follow-up compared to the PA group (ADS 84.1%; PA 92.3%; OR 0.46; 95% CI 0.23-0.91; I2 42.6%). The ADS group was associated with statistically significantly higher odds of reoperation compared to the PA group (ADS 12.4%; PA 5.2%; OR 2.56; 95% CI 1.50-4.35; I2 0%). The rates of technical failure (ADS 2.3%; PA 1.1%; OR 1.11; 95% CI 0.52-2.37; I2 0%) and all-cause mortality (ADS 6%; PA 4.8%; OR 1.35; 95% CI 0.67-2.74; I2 0%) were similar between the two groups. In the subgroup analysis of patients > 60 years old, the ADS was associated with statistically significantly lower odds of fusion compared to the PA group (ADS 72.4%; PA 89.9%; OR 0.24; 95% CI 0.06-0.91; I2 58.7%). ADS fixation is associated with statistically significantly lower odds of fusion at last follow-up and higher odds of reoperation compared to PA. No differences were identified in the rates of technical failure and all-cause mortality. Patients receiving ADS fixation at > 60 years old had significantly higher and lower odds of reoperation and fusion, respectively, compared to the PA group. PA is preferred to ADS fixation for odontoid fractures, with a stronger effect size for patients > 60 years old.