RT Journal Article SR Electronic T1 Classification and grading of muscle injuries: a narrative review JF British Journal of Sports Medicine JO Br J Sports Med FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine SP 306 OP 306 DO 10.1136/bjsports-2014-093551 VO 49 IS 5 A1 Hamilton, Bruce A1 Valle, Xavier A1 Rodas, Gil A1 Til, Luis A1 Pruna Grive, Ricard A1 Gutierrez Rincon, Josep Antoni A1 Tol, Johannes L YR 2015 UL http://bjsm.bmj.com/content/49/5/306.abstract AB A limitation to the accurate study of muscle injuries and their management has been the lack of a uniform approach to the categorisation and grading of muscle injuries. The goal of this narrative review was to provide a framework from which to understand the historical progression of the classification and grading of muscle injuries. We reviewed the classification and grading of muscle injuries in the literature to critically illustrate the strengths, weaknesses, contradictions or controversies. A retrospective, citation-based methodology was applied to search for English language literature which evaluated or utilised a novel muscle classification or grading system. While there is an abundance of literature classifying and grading muscle injuries, it is predominantly expert opinion, and there remains little evidence relating any of the clinical or radiological features to an established pathology or clinical outcome. While the categorical grading of injury severity may have been a reasonable solution to a clinical challenge identified in the middle of the 20th century, it is time to recognise the complexity of the injury, cease trying to oversimplify it and to develop appropriately powered research projects to answer important questions.