The Role of Clinical Examination in Predicting Relevant MRI Findings in Acute Knee Injuries: A Retrospective Study

Abstract The objective of this study was to delineate the usefulness of clinical examination and magnetic resonance imaging (MRI) in acute knee injuries. We aim to establish whether the time period post acute knee injury is related to the diagnostic accuracy of clinical examination and to investigate the strength of specific clinical examination findings in predicting a clinically relevant MRI abnormality. Seventy patients were referred to fracture clinic with an acute knee injury who subsequently went on to be investigated with MRI over 12 months. These patients were retrospectively analyzed looking at the time period they were reviewed, the components that were assessed at physical examination, and the results of their eventual MRI scan looking for any correlation. A greater proportion of patients who were examined at 2 weeks had relevant positive findings on MRI scan, p = 0.03. Range of movement and lateral joint line tenderness were not associated with a positive MRI scan at any period after injury. The presence of a moderate to large effusion was not associated with an MRI abnormality if the examination was within 2 weeks of injury but was if present 2 weeks after injury, p = 0.0001. Range of movement should not form part of the decision making on whether an injury should be investigated with MRI. Joint effusion in isolation within 2 weeks after injury should not be an indication for MRI but a repeat clinical examination in 2 weeks, where if still present, should be investigated with MRI.