OBJECTIVE. The anchoring of the medial meniscus is consistent, whereas the attachment of the lateral meniscus is variable. On routine MRI examinations, we analyzed the prevalence of a distinct fibrous connection between the anterolateral aspect of the lateral meniscus and the iliotibial band-which we have termed the "accessory iliotibial band-meniscal ligament" or "AIML"-and investigated an association between lesions of the lateral meniscus and the presence of an AIML. MATERIALS AND METHODS. We retrospectively reviewed 1019 knee MRI examinations for lesions of the lateral meniscus, presence and morphology of an AIML, and Hoffa edema. Descriptive statistics were applied and univariate analyses were performed to assess the association between the presence of an AIML and meniscal lesions as well as Hoffa edema. RESULTS. An AIML was present, with a mean length of 22.8 mm (range, 12.9-36.8 mm; SD, 5.8 mm), in 13.3% of the patients (136/1019). A lesion of the anterior horn of the lateral meniscus was recorded in 1.2% of patients without an AIML (11/883) and 23.5% of patients with an AIML (32/136; p < 0.001). A lesion of the lateral meniscus body was found in 1.6% of patients without an AIML (n = 14/883) and 16.2% of patients with an AIML (22/136, p < 0.001). Hoffa edema was seen in 0.2% of patients without an AIML (2/883) and 14.0% of patients with an AIML (19/136; p < 0.001). CONCLUSION. The AIML represents an anatomic variant of fixation of the lateral meniscus that is strongly associated with lesions of the lateral meniscus and Hoffa edema.
Keywords: MRI; knee; ligament; meniscus.