364 Traumatic Dens Fracture Patients Comprise Distinct Subpopulations Distinguished by Differences in Age, Sex, and Injury Mechanism and Severity

INTRODUCTION: Dens fractures are an increasingly common cervical fractures, yet their epidemiology and its implications remain under-examined. METHODS: We retrospectively analyzed all traumatic dens fracture patients managed at our institution over a ten year period with respect to demographic, clinical, and outcomes data. Patient subsets were compared across these parameters. RESULTS: 303 traumatic dens fracture patients were identified, who showed a bimodal age distribution with strong goodness of fit centered at age 22.3 ± 5.7 (R = 0.8781) and at 77.7 ± 13.9 (R = 0.9686). A population pyramid demonstrated a bimodal distribution among male patients, but not among female patients, which was confirmed with a strong goodness of fit for two distinct male patient subpopulations age <35 (R = 0.9791) and age =35 (R = 0.8843), but a weak fit for a second female subpopulation age <35 (24.5 ± 14.2, R = 0.5957). Patients age <35 were more likely to be male (82.4% vs. 46.9%, OR = 5.29 [1.54, 17.57], p = 0.0052). Moreover, patients age <35 were more likely to have MVC as their mechanism of injury (64.7% vs. 14.1%, OR = 11.18 [3.77, 31.77], p < 0.0001), were more likely to have a severe trauma injury severity score (17.6% vs. 2.9%, OR = 7.23 [1.88, 28.88], p = 0.0198). There was no difference with respect to underlying fracture morphology, likelihood of undergoing surgery, having concomitant atlas or subaxial fractures, or Nurick scores at presentation. Patients age <35 were less likely to have fracture nonunion at follow (18.2% vs. 53.7%, OR = 0.19 [0.041, 0.76], p = 0.0288). CONCLUSIONS: The dens fracture patient population comprises two subpopulations, distinguished by differences in age, sex, and injury mechanism and severity, with male dens fracture patients demonstrating a bimodal age distribution. While young patients were more likely to high-energy injury mechanisms leading severe trauma, they were less likely to have fracture nonunion at follow up.