steoarthritis (OA) and other rheumatic conditions are the leading cause of disability in the United States. 1 The prevalence of OA of the knee in various countries can be estimated as 18% of men and women as inferred by a recent meta-analysis.2 OA can also result in significant direct and indirect costs, which are higher with greater disability. 3 Current therapeutic options for OA are approved to treat the pain associated with the disorder. The American College of Rheumatology recommends the initial use of nonpharmacologic techniques, such as patient education, weight loss, and physical therapy, followed by pharmacologic therapies such as acetaminophen and cyclooxygenase (COX)-2-specific inhibitors. 4 Intra-articular hyaluronan therapy is recommended for patients who are no longer responsive to nonpharmacologic and pharmacologic treatments or who may be experiencing adverse side effects with nonselective nonsteroidal inflammatory drugs or COX-2-specific inhibitors. 4 Total knee replacement (TKR) is considered a last resort for treatment of OA knee pain in appropriate patients when other therapies fail. According to the National Hospital Discharge Survey published by the U.S. Department of Health & Human Services, approximately 326,000 patients in the United States received a TKR in 2001. 5 In a sample of 6,856 decedents aged ≥65 years, 2.1% were found to have received knee replacements. 6 The cost of knee replacement surgery at patient discharge was reported as $24,045 for 2001. 7 The success of TKR in most patients has been supported by more than 20 years of follow-up data. 8 While TKR is an effective option for OA pain relief for many patients, it is not medically desirable for some patients (age, heart disease, diabetes, pulmonary disease, obesity, or generalized medical debilitation) or is not preferred by others. Additionally, complications of the ABSTRACT BACKGROUND: Total knee replacement (TKR), a last resort for treating knee pain due to osteoarthritis (OA), is not always medically indicated or preferred by many patients. Hylan G-F 20 is a cross-linked hyaluronan derivative approved for the treatment of pain due to OA of the knee after other conservative approaches have failed.OBJECTIVE: The objectives of this study were to (1) determine the effect of hylan G-F 20 on patient need for TKR as measured by time from hylan G-F 20 injection to TKR, and (2) assess patient factors that might influence time from hylan G-F 20 therapy to TKR.METHODS: This is a retrospective case series review of the medical records of patients seen in 1 orthopedic specialty practice. The incidence and time to TKR in patients who were TKR candidates (100% grade IV OA [severe]) treated with 1 or more courses of intra-articular hylan G-F 20 injections (3 weekly injections per course) were determined from October 1997 to November 2003. Survival analysis was used to evaluate time to TKR and the effects of age, gender, ethnicity, body mass index (BMI), and presence of effusion on this outcome. Logistic regression was also used to assess...