Aim: This retrospective study was undertaken to establish the accuracy of magnetic resonance imaging (MRI) in diagnosing medial meniscal, lateral meniscal and anterior cruciate ligament (ACL) tears.

Materials and methods: Sixty patients who had arthroscopic knee surgery following MRI scans were included in the study. MRI findings were then compared with the pathologies noted at subsequent arthroscopy.

Results: In this study, the sensitivity of MRI in diagnosing tears was 67% (ACL), 100% (medial meniscus) and 57% (lateral meniscus) whereas the specificity was 91%(ACL), 46 %(medial meniscus) and 77 % (lateral meniscus).The positive predictive values were 29% (ACL), 68% (medial meniscus) and 57% (lateral meniscus). The negative predictive values were 98% (ACL), 100% (medial meniscus) and 76% (lateral meniscus).

Conclusion: In contrast to some studies, these findings indicate a lower accuracy for MRI scanning in detecting tears of, in particular of the ACL and lateral meniscus. We suggest that where symptoms and clinical findings support one of these diagnoses and arthroscopic therapeutic intervention is contemplated, that MRI scanning is not beneficial. The additional expense and delay in management seems inappropriate given the findings we have demonstrated.