This study aims to analyze the factors affecting in-hospital complication and length of stay in elderly patients with total knee arthroplasty. A total of 8,224 inpatients over 65 years old were selected from the national old inpatient sample data which was produced by Health Insurance Review and Assessment Service in 2016. STATA 12.0 was performed using frequency, chi-square test, t-test, ANOVA and multiple linear and logistic regression analysis. Analysis results show that ages(over 85), Charlson Comorbidity Index, district(metropolitan) for general hospitals and gender, district, beds(100-199) for hospitals are significantly influenced in-hospital complication. Statistically significant factors affecting the length of stay are gender, insurance type, depression, district, bed(300 over) for general hospitals and gender, type of insurance, Charlson Comorbidity Index, depression, district, beds(200-299) for hospitals. Based on these findings, the factors affecting in-hospital complication and length of stay were different depending on the type of medical institution. Accordingly, policymakers should analyze the differences in care behavior depending on the type of medical institution and expand policy and financial support to resolve them.