More postoperative complications and revision surgery after occipitocervical fusion than after atlantoaxial fusion: a retrospective multicenter cohort study

Study Design: A retrospective multicenter cohort study.
Purpose: We sought to determine whether occipitocervical (OC) fusion is followed by more postoperative complications and revision surgery than is atlantoaxial (AA) fusion. We aim to compare postoperative complications and revision surgery associated with OC fusion and AA fusion.
Overview of Literature: OC and AA fusion are established techniques for restoring upper cervical stability. However, the outcomes of the two methods have not been compared.
Methods: This study included 90 patients who underwent upper spinal fusion surgery for mechanical instability, performed by three surgeons in two hospitals from 2011 to 2023; OC fusion was indicated for irreducible AA subluxation, os odontoideum, and severe upper C1 fracture. Of the patients, 38 (mean age, 58.7 years) underwent OC fusion, and 52 (mean age, 62.8 years) underwent AA fusion. To evaluate surgical outcomes, we documented surgical time, intraoperative blood loss, postoperative complications, and the rate of revision surgery. Radiographs were obtained to identify screw malposition, rod breakage, and nonunion. To compare the outcomes of the two techniques, we used the Mann-Whitney U test for continuous variables and the chi-square or Fisher’s exact test for dichotomous variables.
Results: OC fusion took significantly longer (175.4 minutes) than AA fusion (150.7 minutes, p=0.020) and had a higher complication rate (39.5% vs. 11.5%, p<0.0001). The reoperation rate was 23.7% (9/38) after OC fusion and 3.8% (2/52) after AA fusion; the difference was statistically significant (p=0.0073). Average amounts of blood loss were 224 mL during OC fusion and 224 mL during AA fusion; the difference was not significant (p=0.947).
Conclusions: Although OC fusion is indispensable for certain conditions, particularly basilar invagination, it entails more risk than dose AA fusion; the choice of technique thus warrants careful consideration.