Incidence, treatment, and mortality of ankle fractures: a Danish population-based cohort study

Previous studies have shown large variation in the incidence of ankle fractures. Nationwide data covering longer periods is necessary to gain knowledge of the current trends. The aim of this study was to describe the trends in incidence, treatment, and mortality of ankle fracture during a 20-year period.

Ankle fractures in patients ≥ 18 years old were identified in the Danish National Patient Register using the validated diagnosis and surgical procedure codes for ankle fractures. Incidence rates per 100,000 and incidence rate ratio (IRR) are reported with 95% confidence intervals (CI).

We identified 155,740 ankle fractures. The overall mean incidence rate during the period 1997-2018 was 164 (CI 163-165) per 100,000 person-years, being 154 (CI 152-155) for men and 203 (CI 202-205) for women. The incidence rate increased from 155 (CI 131-179) during 1997-2006 to 173 (CI 147-199) during 2007-2018, corresponding to an IRR of 1.12 (CI 1.10-1.12). This increase was primarily driven by an increase in women, with an IRR of 1.21 (CI 1.20-1.23) and for patients above 50 years, with an IRR of 1.22 (CI 1.08-1.10). The proportion of patients surgically treated increased from 21% in 1997-2006 to 25% in 2007-2018. The 1-year mortality risk was higher for patients above 65 years with an ankle fracture compared with the general population of the same age, with an IRR of 1.47 (CI 1.42-1.53).

The incidence of ankle fracture increased from 1997 to 2018, primarily due to an increased incidence in women and in the elderly population. The proportion of surgically treated patients increased from 21% to 26%. Excess mortality after ankle fracture in patients above 65 years was observed.