Trends in Australian knee injury rates: An epidemiological analysis of 228,344 knee injuries over 20 years

BACKGROUND: Acute knee injuries are a key predisposing risk factor for knee osteoarthritis. Public health interventions require in-depth epidemiological evidence to determine which knee injuries are problematic in critical age and sex demographics. METHODS: Descriptive epidemiological analysis of longitudinal data on knee injuries (July 1998 - June 2018) from the National Hospital Morbidity Database in Australia were studied. The main outcomes where the population-related knee injury frequency, incidence per 100,000 and annual growth rate (%) over the 20-year observation period. Age-group and sex differences were also studied to determine demographic-specific trends. FINDINGS: 228,344 knee injuries were diagnosed over the 20-year analysis period. Significantly rising annual incidences were observed for total knee injuries, anterior cruciate ligament (ACL) injuries and knee contusions in males and females. Posterior cruciate ligament (PCL) injuries and knee dislocations were also rising in females, but not males. Greater annual growth rates were observed for females compared to males for total knee injuries, knee contusions, PCL injuries and knee dislocations. Demographic analysis revealed that the highest annual growth rate in injury incidence (10.4%) was observed for ACL injuries in females aged 5-14 years old. INTERPRETATION: Increasing annual incidence of knee injuries was observed over the 20-year period. Males have a higher incidence of knee injury per capita than females, but the gap appears to have narrowed over the 20-year analysis period. Younger Australians show a precipitous rise in the annual number of ACL injuries, particularly for females aged 5-14 years. These trends warrant urgent intervention. FUNDING: None.