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Levels of evidence in orthopaedics
  1. Rob Middleton1,
  2. Andrew Price2
  1. 1 Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford Nuffield, Oxford, UK
  2. 2 Nuffield Orthopaedic Centre, Oxford University, Oxford, UK
  1. Correspondence to Dr Andrew Price, Nuffield Orthopaedic Centre, Oxford University, Oxford OX3 7HE, UK; andrew.price{at}

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In modern surgical practice, the use of evidence based medicine (EBM) to support the delivery of clinical care has become increasingly prevalent. EBM is an approach to decision-making in which a practitioner considers the available evidence and its quality, including the potential for bias, in answering a specific clinical question. Alongside the individual clinician, EBM is used by institutions, public health agencies and regulatory agencies in the creation of protocols, guidelines and approval of interventions on a societal level. As a result, the ability to critically appraise the available evidence is a crucial skill for those in the healthcare arena. Journal of ISAKOS is an exciting new journal that has an important role in presenting evidence to the global Orthopaedic community. In doing this it is important to reflect on the levels of evidence available and their relative merits.

As part of the EBM process, there is a concept of ordering evidence according to its perceived ‘quality’, based on study design and potential for bias. This has resulted in a ‘hierarchy of evidence’, with higher quality sources of evidence at the apex and those more prone to bias at the base. Since the late 1970s, a number of different hierarchies have been published, as well as tools to rate the quality of evidence of a particular report. These have been introduced in response to concerns that the basic hierarchy did not reflect the varying quality of evidence at each level. Across these various hierarchies the overall order is reasonably consistent, with systematic reviews and meta-analysis at the top and expert opinion at the bottom.

It is important to understand the different types of evidence that make up the hierarchy of evidence. Each type has particular strengths and weaknesses, and so each may be more suitable to answering a particular clinical …

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