A 5% sample of Part B Medicare data from 2005-2012 was used in this retrospective , observational study examining the use of intra-articular hyaluronic acid (IA-HA) injections in patients with knee osteoarthritis (OA). Patients were identified based on the presence of specific codes as having knee OA or non-specific OA + knee pain. Patients were further identified as having used IA-HA treatment in the knee joint or having received a knee arthroplasty (KA) with or without at least 1 IA-HA. Additional comparisons were made between time from knee OA to KA and between those who received Euflexxa IA-HA and those who did not. Patient comorbid conditions were also evaluated.