Epidemiology of cruciate ligament surgery in Japan: A retrospective cohort study from 2014 to 2019

Understanding the incidence and trends of cruciate ligament (CL) surgeries in Japan is crucial for providing effective healthcare services. This study aimed to use open data available from the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) to determine the changes over time in CL surgeries and to analyze the characteristics of the Japanese population in terms of sex and age. We retrospectively identified CL surgeries of the knee joint registered from April 2014 to March 2020 using the NDB open data. Data on sex, age, and practice were extracted to determine the number of cases per 100,000 population. Trends in the annual incidence of CL surgeries were evaluated using Poisson regression analysis. In total, 112,686 CL surgeries were performed from 2014 to 2019. Arthroscopic ligament reconstruction accounted for 98% of all the cases. The number of surgeries performed had increased significantly from 16,975 in 2014 to 19,735 in 2019 (P<0.001). Overall, CL surgeries were most common in the 15-19 years age group, followed by the 20-29 years age group. However, these trends differed between males and females. The incidence of CL surgery in Japan has increased, and its characteristics vary by gender and age. These characteristics have been identified not only in younger patients but also in middle-aged and older patients. It would be valuable to further investigate the general patterns of CL surgery in Japan.