Commentary Medical practitioners are presented with substantial data regarding potential interventions for musculoskeletal problems. The American Academy of Orthopaedic Surgeons (AAOS) Clinical Practice Guidelines (CPGs) organize and summarize the available data regarding numerous nonoperative and operative treatments for musculoskeletal problems, including the management of knee osteoarthritis (OA). While the recommendations of the CPGs are often somewhat limited by the lack of quality research, the 2013 AAOS CPG cited moderate evidence against the routine use of hyaluronic acid (HA) injections for the management of symptomatic knee OA. The study by Zhu et al. provides an excellent evaluation of the use of HA injections in Medicare patients, both before and after the CPG was published, as well as an analysis of the financial impact of continued HA use. Knee OA remains highly prevalent and is a substantial economic burden in the United States. Intra-articular injections have long been a mainstay in the nonoperative treatment of the disease; however, recent publications have demonstrated some concerns with corticosteroid injections, particularly when they are performed close to the time of total knee arthroplasty (TKA)1. Unfortunately, similar risk has been demonstrated with HA injections2. The data surrounding the clinical efficacy of HA injections also are quite variable, but in most comparative studies, little benefit is seen over the use of nonsteroidal anti-inflammatory drugs, corticosteroid injections, biologics, or even normal saline solution3,4. The most important finding of the present study is that despite the moderate recommendation against the routine use of HA in the 2013 AAOS CPG, as well as its high cost and questionable clinical efficacy when compared with numerous other treatments, there has not been a significant decline in the use of HA in Medicare beneficiaries. This finding is supported by and expands on an earlier survey study that reported HA to be the most popular choice for management of moderate-grade knee OA5. This finding, while not surprising, is disappointing as it is clear that either the message of the CPG is not being effectively disseminated to the practitioners who are managing knee OA with HA injections, or the evidence is simply being ignored due to a lack of other options for this challenging population of patients. A second important finding of this study is the substantial financial burden that HA injections continue to pose on the health-care system. A cost averaging >$300 million a year is significant and worthy of highlighting. Zhu et al. demonstrated that this cost steadily increased throughout the study period and likely will continue to increase. Given the lack of demonstrated clinical efficacy in large systematic reviews and high-level studies, it is hard to justify these costs for HA use. Recent studies have shown that even emerging treatments such as biologics and platelet-rich plasma (PRP) may be more cost-effective than HA injections6. A finding of the study that may explain some of the discordance between the AAOS recommendations and HA utilization is that advanced practice providers (APPs) contributed significantly to the national increase in utilization that was seen over the study period. Many practices have transitioned interventions such as injections to APPs. It is very possible that evidence from the CPG has not effectively been distributed to APPs. The true cause is likely multifactorial. There are many patients with advanced knee OA who are simply not ready for TKA or are not good candidates for TKA since the requirements for optimization of medical comorbidities continue to become stricter. Many patients will not find any relief from corticosteroid injections, and as long as HA injections are available, they represent another possible therapeutic option, despite the evidence against the routine use of HA. While biologics such as PRP have shown promising benefits in the management of knee OA, insurance companies still do not cover this cost, and many patients cannot afford cash payments for prolonged treatment. Value-based care continues to be the focus of health-care practitioners, health systems, and insurers. When CPGs offer conclusive recommendations based on available evidence, it is worthwhile to evaluate their effects on practice patterns. The trends observed in the study by Zhu et al. demonstrated that despite the high cost and low clinical efficacy of HA injections, in addition to a CPG recommending against its routine use, there has been no appreciable decline in the use of HA injections among Medicare beneficiaries within the 5 years following publication of the CPG. This highlights the importance of wide dissemination of CPGs to physicians and APPs, as well as the need for more cost-effective treatments for knee OA.