Project Summary/Abstract: Evidence-based medicine (EBM) combines the best available practices with clinician experience and patient values. Prior to evidence-based medicine, quality of care was based on adherence to local standard practices given by healthcare providers. This standard was based on what historical practices, and was often anecdotal in nature. Improved means of statistical analysis, especially multivariable analysis, systematic reviews and meta-analysis has helped the advancement EBM. The adoption of EBM tenets has been slow, and acceptance of EBM over eminence-based orthopaedics has suffered. To this end, educating surgeons about the benefits and biases of high level of evidence studies, including randomized control trials (RCTs) and prospective observational studies, will help improve the clinical care of orthopaedic patients. Further, clinical interpretation in practice requires understanding of the Consolidated Standards of Reporting Trials (CONSORT) and Strengthening the Reporting of Observational studies in Epidemiology (STROBE) diagrams. The conflict between EBM and previously accepted standards is evident in several orthopaedic procedures in which EBM has questioned value: viscosupplementation, vertebroplasty, and knee meniscectomy for degenerative meniscal tears. Both RCTs and observational studies have important places in surgical research. A well-done cohort trial may provide greater insight to practical patient care than a RCT that is not applicable to many patients. In addition, observational studies can be particularly useful in addressing questions related to surgical procedures where RCTs cannot be performed or the number of patients necessary to achieve adequate statistical power is too numerous to make the trial practical. Improved education for surgeons reading and reviewing studies is critical to advancing the practice of orthopaedic surgery and the care of surgical patients. Improved understanding of the benefits and biases of studies at the highest levels of evidence, namely RCTs and prospective observational studies, will enable important and much needed advancements in the care of our patients. This symposium will address the strengths and weaknesses of these types of analyses in musculoskeletal care. The recent popularity of registry data for quality purposes will be explored as to how this fits within the hierarchy of evidence and physician/patient decision making. This is especially important given the AAOS emphasis and development of national registries for major orthopaedic procedures.