Diagnostic accuracy of dynamic ultrasound imaging in partial and complete anterior cruciate ligament tears: a retrospective study in 247 patients

Objectives Dynamic ultrasound (US) imaging shows promising possibilities for accurate imaging in diagnosing anterior cruciate ligament (ACL) tears and can be used as a point-of-care test. The aim of this study is to determine the diagnostic accuracy of dynamic US imaging for detecting partial and complete ACL tears. Methods 247 patients presenting with knee complaints, who underwent dynamic US imaging as well as arthroscopy for any intra-articular knee pathology, were retrospectively evaluated. We differentiated between partial and complete ACL tears. Results Dynamic US imaging revealed 95 of 108 arthroscopically confirmed ACL tears (sensitivity 88%, specificity 82%, positive predictive value (PPV) 79%, negative predictive value (NPV) 90%, and diagnostic OR (DOR) of 33.3). Sensitivity of US in the detection of partial ACL tears was 52%, specificity 85%, PPV 52%, NPV 84% and DOR 5.8. Complete ACL tears were depicted with a sensitivity of 79%, specificity of 89%, PPV of 63%, NPV of 95% and DOR 29.8. Multivariate regression analysis adjusting for age (dichotomised per 5 years) and previous knee surgery showed similar DOR. Conclusion The excellent NPV for complete ACL tears indicates that dynamic US imaging can be used as an initial imaging point-of-care test. However, the clinical presentation should be taken into account, especially in case of subtotal tears. Whereas it seems relatively easy to differentiate between (small) partial ACL tears, complete ACL tears and no tears, it seems to be difficult to differentiate subtotal tears from complete tears.