MRI appearance of the distal insertion of the anterior cruciate ligament of the knee: an additional criterion for ligament ruptures

Anterior cruciate ligament tears are frequent and if not diagnosed may lead to relevant patient disability. Magnetic resonance imaging is the method of choice for the non-invasive diagnosis of these tears. Despite the high performance of this method some cases are challenging and the criteria described in the literature are not sufficient to reach a diagnosis. We propose a systematic method for the evaluation of anterior cruciate ligament tears based on the aspect of its distal portion. Magnetic resonance studies of 132 knees were evaluated in correlation with arthroscopy. The performance of the proposed method was compared with that of classic imaging signs of anterior cruciate ligament tear. The impact of image quality and reader expertise on the proposed method and the classic signs of tear were taken into account. This method had a sensitivity and specificity of 91.1% and 82.9% for the detection of abnormal ACLs. The interobserver agreement (kappa) of the proposed method was significantly higher than that of the classic signs at all levels of expertise (0.89 vs 0.76). This method was not influenced by image quality. Distal ACL analysis identified more partial tears and synovialization (granulation scar tissue) than the conventional method (71% vs 58.5% for partial tears and 83.5% vs 58.5% for synovialization). The proposed classification has a high performance and reproducibility for the identification of abnormal anterior cruciate ligament. The results were influenced neither by the level of expertise of the readers nor by the image quality.