Anterior horn of the lateral meniscus: another potential pitfall in MR imaging of the knee.

PURPOSE: To demonstrate that speckled increased signal intensity at the anterior horn of the lateral meniscus near its central attachment site on sagittal magnetic resonance (MR) images of the knee is a normal finding. MATERIALS AND METHODS: In 22 patients (17 male and five female patients; age range, 13-74 years; mean, 38 years) who underwent arthroscopy after MR imaging, knee MR images that showed speckled increased signal intensity at the anterior horn of the lateral meniscus near its central attachment site on two consecutive sagittal proton-density-weighted images were selected for retrospective review. In addition, a review of 11 knee MR examinations of nine healthy volunteers (five men and four women; age range, 27-43 years; mean, 34 years) was performed. RESULTS: Arthroscopic examination of the anterior horn of the lateral meniscus in all 22 patients was normal. Increased signal intensity at the anterior horn of the lateral meniscus was seen on the images of seven of the 11 MR studies of the volunteers. CONCLUSION: Increased signal intensity at the anterior horn of the lateral meniscus near its central attachment site on knee MR images does not represent a meniscal tear.