Fig. 1

The flow diagram illustrates the patient selection process for total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) patients who underwent knee replacement surgery due to osteoarthritis (OA) or rheumatoid arthritis (RA), as well as the propensity score (PS) matching process. It details the methodology used to extract target patients from the Diagnosis Procedure Combination (DPC) database and the subsequent PS matching process for the TKA and UKA cohorts