MR imaging of tears of discoid lateral menisci.

Abstract

OBJECTIVE. The purposeof this study was to determinethe positivepredictivevalue (PPV) for diagnosis of discoid lateral meniscal tear using MR imaging and to describe various patterns of such tears in the knee.SUBJECTS AND METHODS. MR reportsof 77 patients(10â€"67 yearsold) who under went prospective MR imaging that led to a diagnosis of discoid lateral meniscal tear were cor related with arthroscopic results. MR images obtained in 71 patients confirmed to have discoid lateral meniscial tear were retrospectively reviewed for the presence, site, and pattern of discoid lateral meniscal tear, including type of displacement of the torn segment. MR ab normalities were correlated with arthroscopic findings. RESULTS. For the prospective MR interpretations, the PPV for discoidmeniscus was92%. ppv for discoid meniscal tear was 57%. PPVs for individual types ofdiscoid meniscal tears were 46% (peripheral tear, 19/41), 76% (peripheral tear with horizontal tears, 16/21), 56% (horizontal tear, 5/9), 50% (transverse tear, 1/2), 67% (horizontal tear combined with transverse tear, 2/3), and 100% (longitudinal tear, 1/1). Peripheral tear alone and peripheral tear with horizontal tear were the most common types oftears (n = 20, 28%). Multiple tears (n = 34, 48%) were common. Displacement ofthe torn segments was seen in 51 patients (72%).CONCLUSION. MR imaging has a low PPV for diagnosingdiscoid lateral meniscal tear. Peripheral tear alone and peripheral tear with horizontal tear were the most common types of tears, and displacement of the torn segment was frequent. Because of its abnormal structure, the discoid meniscus sustains increased stress, which in creases the incidence of tears and cystic degen eration [15]. MMR imaging of the knee is commonly used to diagnosediscoidmenisci;however,to our knowledge, its reliability has not been criti cally studied. Because of regional anatomic features, the MR imaging pattern of such a tear may be atypical [16].In our practice in Korea, we have encountered repeated instances in which MR findings it ported to represent discoid lateral meniscal tear have not correlated with arthroscopic abnoimali ties. To address these issues, we designed a study to calculate the positive predictive value (PPV) ofMR imagingandtodetermine thevarious pat tems of discoid lateral meniscal tear, with ar throscopy as the standard of reference. Subjects and MethodsFrom 1991 through 1996, 1802 patients at our institution underwent MR imaging of the knee. A database search yielded reports of 156(8.1%) who had evidence of a discoid lateral meniscus with a tearon prospectiveMR imaging.Arthroscopywas subsequently performed in 11 patients (49%, 11 knees) at our institution; these patients (38 males, 39 females; 10â€"61 years old; mean age, 27 years old) form the basis of this study. The right knee was examined in 31 patients and the left knee in 40 patients.

MRI Evaluation of Internal Derangements of Knee Joint

“…Grade 1 and grade 2 lesions indicate mucinous or mucoid intrasubstance degenerative change and are usually encountered after 3 or 4 decade. Due to prominent vascularity in children and young adults misinterpretation as grade 1 or 2 tear is usual [4] [11] . Classification of tears: 1.…”

Results of Arthroscopic Partial Meniscectomy for Lateral Discoid Meniscus Tears Associated with New Technique

“…Magnetic resonance imaging can accurately show a discoid meniscus and reveal a tear. Its positive value in diagnosing discoid lateral menisci has been reported as 92%15). A study by Ryu et al15) involving 77 knees with MRI findings of lateral discoid meniscus tear stated that the most common type of discoid lateral meniscus tear was peripheral tear with horizontal tears.…”

Pathognomic Discoid Medial Meniscus with a Parameniscal Cyst: A Case Report and Literature Review of Anomalous Medial Meniscus Variants

“…Smillie theory states that menisci exist as cartilaginous disc at an early stage in the development and congenital discoid meniscus is attributable to the persistence of the disc shape at varying stages of embryonic development, whereas Kaplan postulated in 1974 that discoid menisci are acquired after birth and are related to congenital alteration in the attachment of the meniscus posterior horn by the meniscofemoral ligament thus making it a pathologic entity rather than a congenital anomaly [2]. Anatomical studies by Clark and Ogden have demonstrated that anterior extensions from both menisci to anterior cruciate ligaments can be present after birth [3].…”

“…It is an extremely rare anomaly with an incidence of 0.1-0.3% [2]. Only 35 cases have been reported in literature so far [3].…”