Because most meniscal tears are not isolated to the red zone, it is understandable that most meniscal surgeries are partial meniscectomies which aim to restore meniscus stability while preserving as much native meniscal tissue as possible, to decrease the risk of osteoarthritis. There are Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), Posterior Instability and Labral Pathology, Imaging Evaluation of the Painful or Failed Shoulder Arthroplasty, Other Entities: PLRI, HO, Triceps, and Plica, MRI-Arthroscopy Correlations in the Overhead Athlete, Acetabular Fossa, Femoral Fovea, and the Ligamentum Teres. Seventy-four cases of bucket-handle tears (mean age, 27.2 11.3 years; 38 medial meniscus and 36 lateral meniscus; 39 concomitant anterior cruciate ligament (ACL) reconstruction) were treated with arthroscopic repair from June 2011 to August 2021. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients.9 The lateral meniscus is more loosely attached than the medial and can translate approximately 11mm with normal knee motion.10. Because there is less pressure on the meniscus there, it is difficult to evaluate the anterior region of the meniscus. discoid lateral meniscus is a relatively uncommon developmental variant These are like large radial tears and can destabilize a large portion of the meniscus. Description. Problems encountered in a discoid medial meniscus are the same as a Disadvantages include increased cost, increased patient time, potential for adverse reactions to contrast agent compared to conventional MRI and lack of joint distention. On examination, there was marked medial joint line tenderness and a large effusion. Tears of the anterior horn of the medial meniscus, an inferior patella plica, and ACL tears can be mistaken for AIMM, but carefully tracing the ligament will help to exclude these conditions. intra-articular structures at 8 weeks gestation. reported.4. in 19916. The posterior horn is always larger than the anterior horn. This is a well-done study with clinical correlation and adequate follow-up. De Smet A. Radiographs are usually not diagnostic, but they may show a Longitudinal (longitudinal, peripheral-vertical) tears run parallel to the circumference of the meniscus along its longitudinal axis, separating the meniscus into central and peripheral portions (Fig. incomplete breakdown of the central meniscus, but this is now disputed, [emailprotected]. medial meniscus, and not be confined to the ACL as seen in an ACL tear. They may not even be apparent with an arthroscopic examination. Pagnani M, Cooper D, Warren R. Extrusion of the Medial Meniscus. To provide the highest quality clinical and technology services to customers and patients, in the spirit of continuous improvement and innovation. Direct and indirect MR arthrography have been shown to be superior to conventional MRI for detection of recurrent meniscal tears in greater than 25% partial meniscectomies and meniscal repairs; however, conventional MRI is commonly used for initial evaluation of the postoperative meniscus with MR arthrography reserved for equivocal cases. Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. Definite surfacing signal or distortion on only one image represents a possible tear. What is a Lateral Meniscus Tear? Following meniscal allograft transplantation (Figure 17), complications occur in up to 21% of procedures, including allograft failure and progressive cartilage loss.19 Repeat operations occur in up to 35% of patients, 12% requiring conversion to total knee arthroplasty. Anatomic variability and increased signal change in this area are commonly mistaken for tears. ligament will help to exclude these conditions.5 In the first Direct intraarticular injection of 20-50 mL of dilute iodinated contrast is performed with rapid image acquisition using multidetector CT with high spatial resolution and multiplanar reformatted images. There was no evidence of meniscal extrusion or a meniscal ghost sign (Fig. The trusted source for healthcare information and CONTINUING EDUCATION. . that this rare condition is also clinically asymptomatic. The medial meniscus is more firmly attached to the tibia and capsule than the lateral meniscus, presumably leading to the increased incidence of tears of the medial meniscus [ 8, 11, 12 ]. Generally, The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. History of medial meniscus posterior horn partial meniscectomy. What are the findings? be misinterpreted for more significant pathology on MRI. 3 is least common. However, recognizing these variants is important, as they can Findings indicate an intact meniscus following partial meniscectomy with normal intrameniscal signal. > 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% no financial relationships to ineligible companies to disclose. Nakajima T, Nabeshima Y, Fujii H, et al. . They are usually due to an acute injury [. menisci develop from this mesenchymal tissue in a site where this tissue 6 months post-operative she had increased pain prompting follow-up MRI. Brody J, Lin H, Hulstyn M, Tung G. Lateral Meniscus Root Tear and Meniscus Extrusion with Anterior Cruciate Ligament Tear. We use cookies to create a better experience. of the menisci can be summarized as providing: Clark and Ogden studied the natural development of the menisci in the The lateral meniscus is more circular with a shorter radius, covering 70% of the articular surface with the anterior and posterior horns approximately the same size. A new longitudinal tear has occurred more centrally in the meniscus (arrowhead) with linear high signal extending to the tibial and femoral surfaces as well as fluid signal and gadolinium contrast in the defect. During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. Zonal variation is also seen in the density of meniscus cells and their phenotypes with a chondrocytic inner zone and fibroblastic outer zone. While this test will show a tear up to 90% of the time, it does not always. 9 The lateral meniscus is more loosely attached than the medial and can translate approximately 11mm with normal knee motion. Surgery is useful if they are unstable and flipping in and out of the joint causing pain. Knee Surg Sports Traumatol Arthrosc. collapse and widening of the medial joint space (Figure 7). 1427-143. The intrameniscal ligament where it diverges from the back of the anterior horn of the lateral meniscus is also a common area misinterpreted as a tear. Most lateral meniscal tears are due to twisting or turning activities or falls. published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). Associated anomalies in a discoid medial Lateral meniscus bucket handle tears can produce the double anterior horn sign or double ACL sign. Sagittal T2-weighted (18B) and fat-suppressed sagittal proton density-weighted sagittal (18C) images demonstrate fluid-like signal in the posterior horn suggestive of a recurrent tear. has shown that 41% of patients with a surgically confirmed torn post-operative meniscus had signal intensity within the meniscus extending into the articular surface which was lower than the signal intensity of gadolinium contrast.14 Like the presence of a line of intermediate T2 signal extending into the articular surface on conventional MRI, diagnosis of a torn post-operative meniscus on MRI arthrography is challenging when the intra-meniscal signal intensity is not as bright as gadolinium contrast. MRI Knee - Sagittal PDFS - Displaced meniscus Part of a torn meniscus can be displaced into another part of the knee joint In this image the anterior part of the meniscus (the anterior horn) is correctly located The posterior horn is displaced such that it is located next to the anterior horn The correct position of the posterior horn is shown 5 In the first instance, tears of the lateral aspect of the anterior horn of the medial meniscus are extremely uncommon and should not be a diagnostic The diagnosis of tears of the anterior horn of the meniscus by magnetic resonance imaging (MRI) is sometimes different from that obtained by arthroscopic examination. Figure 7: Meniscofemoral ligament. However, many clinicians opt to use conventional MRI as the initial postoperative imaging study and reserve MR arthrography for equivocal cases. Best assessed on T2 weighted sequences. Among these 26 studies of an LMRT . The MRI also demonstrated moderate degenerative spurring at the lateral joint compartment, a large knee joint effusion with . That reported case was also associated with Thus, the loss of the lateral meniscus can often lead to rather rapid onset of osteoarthritis. As such, I can count on my hands the number of isolated anterior horn meniscal tears that I have seen at surgery that I felt were symptomatic over the past 5 years. However, the use of MRI arthrography should be considered for post-operative menisci with equivocal findings on conventional MRI as the presence of high gadolinium-like signal within the meniscus would allow for a definitive diagnosis of re-tear. The most common location is the anterior horn-body junction of the lateral meniscus and less commonly in the mid posterior horn or root of the medial meniscus. Proper preoperative sizing of the allograft is critical for surgical success and usually performed with radiographs. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. What is a Grade 3 meniscus tear? On medial posterior root tears there is often 2: On posterior root radial tears of the lateral meniscus, the appearance may be similar to radial tears in other locations. posterior horn usually measures 12 mm to 16 mm in the sagittal plane in There is no universally accepted system for classifying meniscal tear patterns. A Wrisberg type variant has not been documented in The discoid lateral-meniscus syndrome. In this case, we can determine that there is a new tear in a different location. This high rate of success, however, may not apply to anterior horn tears, which occur much less commonly than posterior horn and meniscal body tears. It is often explained by fibers of the anterior cruciate ligament and the covering synovium . 2006;239(3):805-10. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. of the Wrisberg ligament in patients with a complete lateral discoid The incidence of lateral meniscus posterior root tears was approximately 4 times higher than of medial meniscus posterior root tears in both primary (12.2% vs 3.2%) and revision (20.5% vs 5.6%) ACLRs. Meniscal root tears are a type of meniscal tear in the knee where the tear extends to either the anterior or posterior meniscal root attachment to the central tibial plateau. Interested in Group Sales? Evaluation of postoperative menisci with MR arthrography and routine conventional MRI. Magnetic resonance imaging (MRI) is the most accurate imaging technique in the diagnosis of meniscal lesions and represents a standard tool in knee evaluation. The ideal technique for imaging the postoperative meniscus is a matter of active controversy and depends on the operation performed, surgeon preference and clinical question (concern for recurrent meniscal tear versus articular cartilage). Resnick D, Goergen TG, Kaye JJ, et al. The lateral meniscus attaches to the popliteus tendon and capsule via the popliteomeniscal fascicles at the posterior horn and to the medial femoral condyle by the meniscofemoral ligaments. and ACL tears can be mistaken for AIMM, but carefully tracing the partly divides a joint cavity, unlike articular discs, which completely to the base of the ACL or the intercondylar notch. mimicking an anterior horn tear. The medial meniscus is asymmetrical with a larger posterior horn. Menisci are present in the knees and the from AIMM. Discoid lateral meniscus: Prevalence of peripheral rim instability. It is important to know the age of the patient when interpreting the MRI. Heron, D, Bonnard C, Moraine C,Toutain A. Agenesis of cruciate Similarly, the postoperative meniscus is at increased risk for a recurrent tear either at the same or different location due redistribution of forces and increased stress on the articular surface. also found various MRI characteristics highly specific for detection of a recurrent tear including a line of intermediate-to-high signal or high signal through the meniscus extending into the articular surface on T2-weighted images with 95.8% specificity and change in the signal intensity pattern through the meniscus on intermediate weighted or T2-weighted images when compared to the baseline MRI with 98.2% specificity. of the meniscus. This case features the following signs of meniscal tear: Case courtesy, Prof. Dr. Khaled Matrawy, Professor of radiology, Alexandria university, Egypt. Meniscus tears are either degenerative or acute. Sagittal proton density-weighted image (5A) through the medial meniscus at age 12 shows the initial horizontal tear in the posterior horn (arrow) subsequently treated with partial meniscectomy. Bilateral hypoplasia of the medial meniscus has also been Meniscal tears were found on MRI or arthroscopy in all 28 patients with a lateral cyst overlying the body or posterior horn of the lateral meniscus, whereas a tear was found on MRI or arthroscopy in only 14 (64%) of 22 patients with cysts adjacent to or extending to the lateral meniscus anterior horn (p = 0.006). Anomalous They were first described by M J Pagnaniet al. The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). This arises from the posterior horn of the lateral meniscus and attaches to the lateral aspect of the medial femoral condyle. How I Diagnose Meniscal Tears on Knee MRI. Recent evidence suggests that decreased extrusion may correlate to better clinical outcomes.18. The medial meniscus is more firmly attached to the tibia and capsule than the lateral meniscus, presumably leading to the increased incidence of tears of the medial meniscus [ 8, 11, 12 ]. meniscal diameter. Grades 1 and 2 are not considered serious. Results: In a consecutive series of 301 ACL reconstructions, 50 patients (33 male, 17 female) with a mean age of 29.6 years (range, 14-61 years) were diagnosed with a medial meniscal ramp lesion at . Root tears are associated with a high risk for osteoarthritis. Samoto N, Kozuma M, Tokuhisa T, Kobayashi K. Diagnosis of discoid lateral meniscus of the knee on MR imaging. Direct MR arthrography requires intraarticular injection of 20-50 mL of dilute gadolinium contrast prior to imaging which distends the joint capsule and offers a high signal to noise ratio on T1-weighted images with contrast extension into the meniscal substance indicating a recurrent tear or an unhealed repair. It is believed that discoid According to one source, they are thought to account for ~10% of all arthroscopic meniscectomies 5. variant, and discoid medial meniscus. Mild irregularities of the meniscal contour may be present, particularly in the first 6-9 months after surgery which tend to smooth out and remodel over time.15 For partial meniscectomies involving less than 25% of the meniscus, conventional MRI is used with the same imaging criteria for evaluating a tear as the native meniscus linear intrasubstance increased signal extending to the articular surface, visualized on 2 images, either consecutively in the same orientation or in the same region in 2 different planes or displaced meniscal fragment (based on the assumption that imaging is spaced at 3 mm intervals). Evaluate the TCO of your PACS download >, 750 Old Hickory Blvd, Suite 1-260Brentwood, TN 37027, Focus on Musculoskeletal and Neurological MRI, Meniscal tears: the effect of meniscectomy and of repair on intraarticular contact areas and stress in the human knee. Exam showed a mild effusion and medial joint line tenderness. Irrespective of the repair approach or repair devices used, diagnostic criteria for a recurrent tear remains the same fluid signal or contrast extending into the meniscal substance. meniscus. Radiographic knee dimensions in discoid lateral meniscus: Comparison with normal control. Diagnosis of meniscal tears on MRI improves when these guidelines are followed to optimize signal-to-noise ratio: high-field-strength magnets are preferable (1.5 T and stronger); a high-resolution surface coil should be used; the field of view should only encompass the necessary structures and routinely be 16 cm or less; image slices should not be too thick (34 mm); and the matrix size should be at least 256192 or higher [, A normal meniscus is low signal on all sequences. Anterior lateral cysts extended . Magnetic resonance imaging (MRI), was performed in another facility and, showed normal medial and lateral menisci except for the absence of a medial posterior root insertion both on coronal and on sagittal images. They maintain a relatively constant distance from the periphery of the meniscus [. least common is complete congenital absence of the menisci. congenital anomalies affect the lateral meniscus, most commonly a When the cruciate These features constitute O'Donoghue unhappy triad. frequently. horn of the lateral meniscus, and oblique tear orientation In the present study, the patients analyzed came from the have been the most difficult for imaging planes to visualize same geographical area . Meniscal tears are common and often associated with knee pain. Horizontal (degenerative) tears run relatively parallel the tibial plateau. A tear of the meniscal root means the tear is near where it attaches to the bone, usually far in the back. Presentation - Middle-older aged individuals, non-traumatic, progressive onset of pain. 1. Check for errors and try again. pretzels dipped in sour cream. Radial Meniscal Tear: Pearls May be degenerative or traumatic, vertical, millimeters in size, on the inner edge of the lateral meniscus more commonly than the medial meniscus The anterior meniscofemoral ligament (Humphrey ligament) attaches proximally on the medial femoral condyle, inferior to the PCL insertion. Indirect MR arthrography is less commonly used and relies on excretion of intravascular gadolinium into the joint through synovial cells after intravenous administration of gadolinium contrast 20-90 minutes prior to the MRI exam. diagnostic dilemma, as the AIMM band will be seen to extend to the One important reason for such discrepancies is a failure to understand the transverse geniculate ligament of the knee (TGL).
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