Radial meniscal tears: Significance, incidence, and MR appearance

OBJECTIVE. The purpose of this study was to assess the prevalence of radial meniscal tears at arthroscopy and the ability of MRI to detect radial tears preoperatively. In addition, the ability of four radiologic signs to detect radial tears was assessed. Those signs are the truncated triangle, cleft, marching cleft, and ghost meniscus signs. MATERIALS AND METHODS. Arthroscopy of the knee was performed by a single orthopedic surgeon on 196 consecutive patients. The surgeon noted each radial tear he encountered. The MR images that were obtained at our institution were reviewed, whereas those patients who were imaged elsewhere were excluded. The preoperative MRI reports were reviewed to assess the ability to prospectively identify radial meniscal tears. In addition, a retrospective analysis of the MRI studies was performed by two radiologists in which four radiologic signs were applied to detect radial tears. RESULTS. Twenty-nine patients (15%) had radial tears at arthroscopy. Eighteen of the 29 patients had their imaging performed at our institution and were selected for review. There were 19 radial tears found at surgery. Seven (37%) of the 19 tears were identified as radial prospectively. Retrospectively, using the four signs for radial tears, reviewers identified 17 (89%) of 19 radial tears. CONCLUSION. A more accurate preoperative diagnosis may be rendered using the four described signs to detect radial tears, thus allowing informative preoperative counseling and consideration of new therapies that are available for radial meniscal repair.