Correlation between osteoarthritis of the atlantoaxial facet joint and a high‐riding vertebral artery

BACKGROUND: A high-riding vertebral artery (HRVA) is an intraosseous anomaly that narrows the trajectory for C2 pedicle screws. The prevalence of a HRVA is high in patients who need surgery at the craniovertebral junction, but reports about HRVAs in subaxial cervical spine disorders are limited. We sought to determine the prevalence of HRVAs among patients with subaxial cervical spine disorders to elucidate the potential risk for VA injury in subaxial cervical spine surgery. METHODS: We included 215 patients, 94 were with a main lesion from C3 to C7 (subaxial group) and 121 were with a main lesion from T1 to L5 (thoracolumbar group). A HRVA was defined as a maximum C2 pedicle diameter of < 3.5 mm on axial CT. The sex, age of patients, body mass index (BMI), osteoarthritis of the atlantoaxial (C1-2) facet joints, and prevalence of a HRVA in the 2 groups were compared and logistic regression was used to identify the factors correlated with a HRVA. RESULTS: The patients in the subaxial group were younger than those in the thoracolumbar group, but their sex and BMI did not differ significantly between the 2 groups. The mean osteoarthritis grade of the C1-2 facet joints of patients in the subaxial group was significantly higher than that in those in the thoracolumbar group. A HRVA was found in 26 patients of 94 (27.7 %) in the subaxial group and in 19 of 121 (15.7 %) in the thoracolumbar group. The prevalence of a HRVA in the subaxial group was significantly higher and osteoarthritis of C1-2 facet joints correlated significantly with a HRVA. CONCLUSIONS: The prevalence of a HRVA in patients with subaxial cervical spine disorders is higher than in those without and osteoarthritis of the C1-2 facet joints is correlated with a HRVA.