Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity). These risk factors are particularly important in weight-bearing joints, and modifying them may present opportunities for prevention of osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 1 of a two-part summary of a National Institutes of Health conference. The conference brought together experts on osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 1 focuses on a new understanding of what osteoarthritis is and on risk factors that predispose to disease occurrence. It concludes with a discussion of the impact of osteoarthritis on disability.

Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population.

Objective To develop an evidence‐based guideline for the comprehensive management of osteoarthritis (OA) as a collaboration between the American College of Rheumatology (ACR) and the Arthritis Foundation, updating the 2012 ACR recommendations for the management of hand, hip, and knee OA. Methods We identified clinically relevant population, intervention, comparator, outcomes questions and critical outcomes in OA. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available educational, behavioral, psychosocial, physical, mind‐body, and pharmacologic therapies for OA. Grading of Recommendations Assessment, Development and Evaluation methodology was used to rate the quality of the evidence. A Voting Panel, including rheumatologists, an internist, physical and occupational therapists, and patients, achieved consensus on the recommendations. Results Based on the available evidence, either strong or conditional recommendations were made for or against the approaches evaluated. Strong recommendations were made for exercise, weight loss in patients with knee and/or hip OA who are overweight or obese, self‐efficacy and self‐management programs, tai chi, cane use, hand orthoses for first carpometacarpal (CMC) joint OA, tibiofemoral bracing for tibiofemoral knee OA, topical nonsteroidal antiinflammatory drugs (NSAIDs) for knee OA, oral NSAIDs, and intraarticular glucocorticoid injections for knee OA. Conditional recommendations were made for balance exercises, yoga, cognitive behavioral therapy, kinesiotaping for first CMC OA, orthoses for hand joints other than the first CMC joint, patellofemoral bracing for patellofemoral knee OA, acupuncture, thermal modalities, radiofrequency ablation for knee OA, topical NSAIDs, intraarticular steroid injections and chondroitin sulfate for hand OA, topical capsaicin for knee OA, acetaminophen, duloxetine, and tramadol. Conclusion This guideline provides direction for clinicians and patients making treatment decisions for the management of OA. Clinicians and patients should engage in shared decision‐making that accounts for patients’ values, preferences, and comorbidities. These recommendations should not be used to limit or deny access to therapies.

Objective. To develop an evidence-based guideline for the comprehensive management of osteoarthritis (OA) as a collaboration between the American College of Rheumatology (ACR) and the Arthritis Foundation, updating the 2012 ACR recommendations for the management of hand, hip, and knee OA.Methods. We identified clinically relevant population, intervention, comparator, outcomes questions and critical outcomes in OA. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available educational, behavioral, psychosocial, physical, mind-body, and pharmacologic therapies for OA. Grading of Recommendations Assessment, Development and Evaluation methodology was used to rate the quality of the evidence. A Voting Panel, including rheumatologists, an internist, physical and occupational therapists, and patients, achieved consensus on the recommendations.Results. Based on the available evidence, either strong or conditional recommendations were made for or against the approaches evaluated. Strong recommendations were made for exercise, weight loss in patients with knee and/or hip OA who are overweight or obese, self-efficacy and self-management programs, tai chi, cane use, hand orthoses for first carpometacarpal (CMC) joint OA, tibiofemoral bracing for tibiofemoral knee OA, topical nonsteroidal antiinflammatory drugs (NSAIDs) for knee OA, oral NSAIDs, and intraarticular glucocorticoid injections for knee OA. Conditional recommendations were made for balance exercises, yoga, cognitive behavioral therapy, kinesiotaping for first CMC OA, orthoses for hand joints other than the first CMC joint, patellofemoral bracing for patellofemoral knee OA, acupuncture, thermal modalities, radiofrequency ablation for knee OA, topical NSAIDs, intraarticular steroid injections and chondroitin sulfate for hand OA, topical capsaicin for knee OA, acetaminophen, duloxetine, and tramadol.Conclusion. This guideline provides direction for clinicians and patients making treatment decisions for the management of OA. Clinicians and patients should engage in shared decision-making that accounts for patients' values, preferences, and comorbidities. These recommendations should not be used to limit or deny access to therapies.Guidelines and recommendations developed and/or endorsed by the American College of Rheumatology (ACR) are intended to provide guidance for patterns of practice and not to dictate the care of a particular patient. The ACR considers adherence to the recommendations within this guideline to be voluntary, with the ultimate determination regarding their application to be made by the clinician in light of each patient's individual circumstances. Guidelines and recommendations are intended to promote beneficial or desirable outcomes, but cannot guarantee any specific outcome. Guidelines and recommendations developed and endorsed by the ACR are subject to periodic revision, as warranted by the evolution of medical knowledge, technology, and practice. ACR recommendations are...

Osteoarthritis (OA) is a disease with a truly formidable impact. As the most common form of arthritis, it accounts for more dependency in walking, stair climbing, and other lower extremity tasks than any other disease, especially in the elderly (1). Its economic costs are impressive. Yelin (2) summarized data from several studies and estimated the cost of OA in the US at $15.5 billion (in 1994 dollars), roughly 3 times the cost of rheumatoid arthritis. More than half of the OA costs are due to work loss.As a chronic disease with a multifactorial etiology that includes modifiable risk factors, OA could, in theory, be prevented. To weigh the prospects for preventing OA, investigators have turned to epidemiology, i.e., the study of disease in human populations and its association with individual and environmental characteristics. The foundation of our understanding of OA epidemiology emanatcd from cross-sectional population-based studies conducted by Kellgren and Lawrence in the 1950s in Britain. After a long hiatus, a large number of cohort-based epidemiologic studies, many also community-based, were initiated in the mid-1980s and later. These have begun to provide a wealth of new insights into the risk factors for disease. Some of these studies have now begun to produce longitudinal information that could facilitate valid inferences about causation. When risk factors are consistently identified among epidemiologic studies as preceding disease occurrence, these factors can reasonably be identified as causes of disease. The present review arises in the context of this burgeoning sct of high-quality studies, many of them longitudinal, that provide important new insights, particularly with regard to disease prevention. This review will focus on 2 separate, but related, issues. First, we will review the current state of knowledge about OA epidemiology based on cross-sectional and early longitudinal evidence, concentrating on selected recent advances such as studies of racial differences and reports on lifestyle and environmental risk factors tied to disease occurrence. Second, using these data, we will suggest approaches to disease prevention. Anticipating the prevention focus, our discussion of risk factors for disease will necessarily concentrate on modifiable risk factors for OA, although demographic risk profiling may facilitate the selection of high-risk populations at whom efforts at prevention should be targeted. Genetic studies promise to identify persons and groups at high risk of OA. For comprehensive reviews of OA epidemiology, the reader is referred to other sources (3,4). This review will focus on knee and hip OA, which together account for more lower extremity disability among the US elderly than any other disease. These are also the sites in which we have accumulated the most information regarding disease risk factors. Recent data from the Framingham Study suggest that symptomatic knee OA (defined as pain on most days plus positive findings on a radiograph of the symptomatic knee) occurs in 6.1% of adult...