Magnetic resonance imaging, scintigraphy, and arthroscopic evaluation of traumatic hemarthrosis of the knee

Forty patients with traumatic knee hemarthrosis were examined within 1 week after injury and observations made with magnetic resonance imaging, scintigraphy, arthroscopic evaluation, radiography, and physical examination were compared. Thirty-four patients (85%) had anterior cruciate ligament injuries according to the arthroscopic findings and 28 (83%) of these had associated meniscal tears, Magnetic resonance imaging confirmed the arthroscopic findings, especially if only meniscal tears that required surgery were taken into account (sensitivity, 94% for the lateral and 83% for the medial meniscus), However, the specificity of magnetic resonance imaging was only 29% and 27% for the lateral and medial menisci, respectively, and the accuracy was 28% and 50%, respectively. Marrow edemas, or bone bruises, were seen on magnetic resonance imaging in 80% of the patients and were mainly seen in the lateral compartment. Bone scans correlated well with magnetic resonance imaging findings of marrow edemas. Plain radiographs were normal in all but one case. We show that magnetic resonance imaging does not add information on the status of the anterior cruciate ligament compared with the clinical examination, and that it may be as good as arthroscopic evaluation for the diagnosis of meniscal tears that require surgery.