Pseudotear Sign of the Anterior Horn of the Meniscus

PURPOSE: To observe the morphology of the transverse geniculate ligament of the knee (TGL) by magnetic resonance imaging (MRI) and to analyze the cause of the pseudotear sign of the anterior horn of the meniscus caused by the TGL. METHODS: Patients who underwent MRI examination of the knee joint in the orthopaedics department of our hospital from July 2016 to August 2019 were identified. The occurrence rate, length, width, thickness, cross-sectional shape, pattern, appearance, and position relative to the anterior horn of the lateral and medial meniscus and anatomical variations were observed by multiplane and multisequence MRI. The frequency and cause of the pseudotear sign also were observed. RESULTS: The data of 101 patients were analyzed. Among them, 60 were male, and 41 were female. The average age was 42.01 (18-75) years. The occurrence rate of the TGL was 67.3% (68/101), the average length was 38.75 ± 3.56 mm, the median coronal diameter was 1.79 ± 0.60 mm, the median sagittal diameter was 1.88 ± 0.35 mm, and the cross-sectional morphology was mostly oval and round. There were 5 types of TGL connection to the anterior horn of the medial meniscus: type 1, located at the front edge; type 2, located at the upper front edge; type 3, located at the upper edge; type 4, located at the back upper edge; and type 5, was located at the back edge of the anterior horn of the medial meniscus. There was only one type of TGL insertion into the anterior horn of the lateral meniscus, located at the anterior superior edge of the anterior horn of the lateral meniscus. There were 4 cases of the pseudotear sign in the anterior horn of the meniscus, 3 in the lateral meniscus and 1 in the medial meniscus. The pseudotear sign of the anterior horn of the meniscus caused by the TGL was observed at a rate of 5.88% (4/68). CONCLUSIONS: In MRI examination of the knee, the anterior horn of the meniscus sometimes shows a pseudotear sign. According to the shape and route of the TGL on MRI and the direction and position of the pseudotear sign of the anterior horn of the meniscus, true and false tears of the anterior horn of the meniscus can be identified. LEVEL OF EVIDENCE: Level III, diagnostic study (retrospective, noncomparative, observational case series without a consistently applied reference "gold" standard).