Trends and Regional Differences in Usage of Primary External Fixation From 2018 to 2022 in Japan: A Retrospective Observational Study Using Open Data from the National Database of Health Insurance Claims

Background Primary external fixation (EF) is a crucial method in orthopedic trauma, particularly for complex fractures with soft tissue damage. Despite its importance in damage control surgery, the patterns of EF use in Japan remain underexplored. This study aimed to elucidate the trends and regional differences in EF usage for fracture treatment in Japan and identify factors associated with its variation across regions. Methods We analyzed data from the National Database of Health Insurance Claims (NDB) covering inpatient surgeries from 2018 to 2022. The primary outcome was the EF usage ratio, calculated as the number of primary EFs procedures divided by the total number of internal fixations. The trend of the EF usage ratio over five-year period was assessed by Cochrane-Armitage trend test for temporal trends. We also evaluated the associations between EF usage and factors such as population, region, and emergency care availability. Results A total of 610,326 internal fixations and 29,546 EF procedures were identified, with the EF usage ratio increasing from 4,532 out of 119,223 cases (3.8%) in 2018 to 6,861 out of 126,000 cases (5.4%) in 2022 (p < 0.01). Regional EF usage in total of five-year period ranged from 228 out of 8,103 cases (2.8%) in Oita to 814 out of 9,075 cases (9.0%) in Nagasaki, representing a threefold difference. While 12 prefectures showed statistically significant increases in EF usage, no specific factors were found to explain the regional variations in EF utilization. Conclusion EF usage in Japan has risen over the past five years, with notable regional differences. Further research is needed to identify the causes of these variations and promote consistent trauma care across the country.