The role of preoperative magnetic resonance imaging in internal derangement of the knee.

We attempted to compare the accuracy of our clinical examination and the usage of magnetic resonance imaging (MRI) in evaluating patients suspected of having internal derangement of the knee who were seen in our Orthopaedic clinic. This was done using the findings of arthroscopy as the 'gold standard'. The accuracy of MRI in detecting cruciate ligament tears was between 80-96% against 82-93% for clinical examination. MRI accuracy for meniscus injuries was 80-84% compared to 48-65% for clinical examination. We thus propose that MRI examination is an effective first-line investigation for patients with suspected internal knee derangement, especially menisci injuries; allowing arthroscopy to be reserved for patients in whom surgery is truly indicated.