Epidemiology of Atlas Fractures in the United States: A 20-year Analysis

Introduction: Fractures of the atlas represent a large portion of cervical spine trauma in the geriatric population. With an aging and more active population, it is expected that the number of patients sustaining atlas fractures is increasing. However, epidemiologic data regarding the incidence of atlas fractures in large populations are scarce. The aim of this study was to investigate the incidence and demographic characteristics of patients with fractures of the atlas in the United States (US) over the last 20 years.

Materials And Methods: This descriptive epidemiology study retrospectively analyzed the National Electronic Injury Surveillance System database to identify cases of atlas fractures presenting to US Emergency Departments (EDs) from 2001 to 2020. Annual and overall numbers of fractures and fracture incidence rates, patient demographics (age, gender, race), and injury characteristics (mechanism, associated injuries) were analyzed. Incidence rates are expressed as the number of fractures per million at-risk person-years. Patients were split into four different age groups for comparisons (<18, 18-64, 65-79, 80+ years).

Results: An estimated 38,092 cases of acute atlas fractures were identified, representing 11.1% of all cervical fractures and corresponding to an overall incidence rate of 6.2. Slightly more than half (54%) occurred in females and the mean age was 71 years. Overall, a majority (64%) of cases occurred in patients > 70 years old. There was substantial increase in incidence rate with age (<18 years: 0.7; 18-64 years: 2.6; 65-79 years: 17.1; 80 + years: 71.8). The most common injury mechanism was a low-energy fall (74%). Overall, only 42% of atlas fractures were isolated injuries, with 58% of patients sustaining at least one concomitant injury and 48% sustaining at least one additional fracture. Accounting for population growth yielded a significantly increasing incidence over the study period from 1.7 in 2001 to 13.4 in 2020 (annual percent increase = 11, < 0.00001). Disproportionately large increases in incidence rates were observed in the oldest patient groups.

Conclusions: Atlas fractures occur in older patients and are often associated with concomitant injuries to the head and spine. These types of fractures are increasing in the US, especially among the elderly. The annual incidence increased nearly 700% over the course of the study period and in 2020 was over 13 per million overall. In elderly patients >80 years old, the most recent annual incidence rate was over 157 per million.