Hierarchy of evidence: where observational studies fit in and why we need them

J Bone Joint Surg Am. 2009 May;91 Suppl 3:2-9. doi: 10.2106/JBJS.H.01571.


Although randomized controlled designs are considered the so-called gold standard in medical trials and sit atop the hierarchy of evidence in evidence-based medicine, there are situations in which they are impractical or unethical to undertake, especially in surgical trials. Then, observational studies often provide the best source of information. In this paper, we use examples from the literature to explain the importance of observational studies in furthering the boundaries of orthopaedic surgery and knowledge of musculoskeletal disorders.

MeSH terms

  • Biomedical Research / methods*
  • Clinical Trials as Topic*
  • Evidence-Based Medicine*
  • Humans
  • Observation*
  • Orthopedics*
  • Randomized Controlled Trials as Topic
  • Research Design*