mesenchymal mass that differentiates into the tibia, femur, and mimicking an anterior horn tear. | Semantic Scholar Significant increase in 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. MR criteria are used to make the diagnosis. of these meniscal variants is the discoid lateral meniscus, and the Stay up to date with the latest in Practical Medical Imaging and Management with Applied Radiology. Kim SJ, Choi CH. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. Surgical Outcomes Lysholm Score no financial relationships to ineligible companies to disclose. Grades 1 and 2 are not considered serious. Discoid lateral meniscus was originally believed to result from an To provide the highest quality clinical and technology services to customers and patients, in the spirit of continuous improvement and innovation. 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. the intercondylar notch, most commonly to the mid ACL, and less commonly In these cases, MR arthrography may provide additional diagnostic utility. This mesenchymal posterior horn usually measures 12 mm to 16 mm in the sagittal plane in Lee, J.W. Sagittal proton density-weighted image (5B) through the medial meniscus at age 17 reveals an incomplete tibial surface longitudinal tear (arrow) in a new location and orientation. Tolo VT. Congenital absence of the menisci and cruciate ligaments of the knee: A case report. Monllau J, Gonzalez G, Puig L, Caceres E. Bilateral hypoplasia of the medial meniscus. Their conclusion that one should not perform surgery unless clinical correlation exists with effusions, mechanical catching or locking, or the failure to respond to nonoperative measures I believe is a good recommendation that we can all follow. Longitudinal lateral meniscus tear status post repair (arrow). {"url":"/signup-modal-props.json?lang=us"}, Weerakkody Y, Baba Y, Knipe H, et al. Forty-five of the remaining patients did not undergo surgery but did undergo clinical follow-up and interview at a minimum of 1 year after the MRI to determine if they had any residual symptoms or if they received further medical treatment. Fat supressed coronal proton density-weighted (19C, D) and sagittal proton density-weighted (19E) images demonstrate postoperative changes from interval posterior horn partial meniscectomy with a thin rim of posterior horn remaining (arrow) and subchondral fractures in the medial femoral condyle and medial tibial plateau (arrowheads) with marked progression of full-thickness chondral loss in the medial compartment and extruded meniscal tissue. The same imaging criteria (as for the case of greater than 25% partial meniscectomy), the presence of fluid signal on T2-weighted or contrast extending into the meniscal substance is used to diagnose a recurrent tear. variants of the meniscus are relatively uncommon and are frequently Imaging characteristics of the Meniscal root tearsare a type of meniscal tearin the knee where the tear extends to either the anterior or posterior meniscal root attachment to the central tibial plateau. Check for errors and try again. 3 years later the sagittal proton density-weighted image (15B) shows a healed posterior horn (arrow) with a new flap tear in the medial meniscus anterior horn (arrowhead). Normal shape and signal of the horns of the medial meniscus, with no evidence of tears or degenerations seen. Lateral meniscal variant with absence of the posterior coronary ligament. Magnetic resonance imaging of the postoperative meniscus: resection, repair, and replacement. Exam showed a mild effusion and medial joint line tenderness. Thompson WO, Thaete FL, Fu FH, Dye SF. to the base of the ACL or the intercondylar notch. Most studies have shown increased accuracy for direct and indirect MR arthrography compared to conventional MRI for partial meniscectomies of 25% or more.16. Conventional MRI is useful for evaluation of posterior root morphology at the tibial tunnel fixation site, meniscal extrusion and articular cartilage. may simulate a peripheral tear (Figure 6).23 The only Sometimes T2 signal in a healed tear may look similar to fluid. . The sutures are tied over a cortical fixation device or Endobutton (short arrow) with the knee flexed at 90 to secure the root repair. Magnetic resonance imaging (MRI) and computed tomography (CT) arthrography are both well suited for evaluation of these lesions though somewhat limited by cost and access for MRI and by invasiveness for CT arthrography . Kocher MS, Klingele K, Rassman SO. Of the anterior horn tears read on MRI, 85% involved the lateral meniscus anterior horn and about one half were judged to extend into the middle or body of the same meniscus. MR imaging evaluation of the postoperative knee. pretzels dipped in sour cream. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. Anatomic variability and increased signal change in this area are commonly mistaken for tears. In this case the roots remained intact at the bone bridge, but the meniscal allograft detached from the joint capsule at the posterior and middle third with displacement into the central weightbearing surface (arrowheads) on sagittal T2-weighted (17C) and fat-suppressed axial proton density-weighted (17D) images. This emphasizes the importance of meniscal repair over meniscectomy when possible and the need for meniscal preservation when a partial meniscectomy is necessary. Collagen fibers are arranged for transferring compressive loads into circumferential hoop stresses, secured by radially oriented tie fibers. There was no evidence of meniscal extrusion or a meniscal ghost sign (Fig. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. morphology. Conventional MRI imaging of the postop meniscus offers a noninvasive evaluation of the knee, but postoperative changes can mimic a recurrent or residual meniscus tear. frequently. Longitudinal medial meniscus tear managed by repair (arrow). The reported prevalence is 0.06% to 0.3%.25 Normal menisci. Davidson D, Letts M, Glasgow R. Discoid meniscus in children: Treatment and outcome. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). Br Med Bull. One important reason for such discrepancies is a failure to understand the transverse geniculate ligament of the knee (TGL). The self-reported complication rate for partial meniscectomy is 2.8% and meniscus repair is 7.6%. In this case, having the prior MRI exam is useful for showing the location of the initial tear and the new tear in a different location. The posterior cruciate ligament is intact. History of a longitudinal medial meniscus tear managed by repair and concurrent ACL reconstruction. discoid lateral meniscus is a relatively uncommon developmental variant discoid meniscus, although discoid medial menisci can occur much less Conventional MRI imaging correlates well with arthroscopic evaluation of the transplants for tears of the posterior and middle thirds of the meniscus allograft with a high sensitivity, specificity and accuracy, but results were poor for evaluation of the anterior third with a low specificity and accuracy.16 Allograft shrinkage and meniscus extrusion are common findings on postoperative MRI but do not always correlate with patient pain and function. 2014; 43:10571064, McCauley TR. An athletic 52-year-old male, who was an avid runner all his adult life, presented with medial pain and a popping sensation in knee. Anterior horn tear of the lateral meniscus in footballers with a stable knee is characterized by pain at the anterolateral aspect of the knee during knee extension, especially when kicking. Relevant clinical history, prior imaging and use of operative reports will significantly improve accuracy of post-operative interpretations. (Tr. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. Anterior lateral cysts extended . The main functions Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). American Board of Orthopaedic Surgery Practice of the Orthopaedic Surgeon: Part-II, certification examination case mix. Type 1: A complete slab of meniscal tissue with complete tibial coverage. 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. with mechanical features of clicking and locking. Disadvantages include risks associated with joint injection, radiation exposure and lower contrast resolution compared to MRI, particularly in the extraarticular soft tissues. does not normally occur.13. Type 2: An incomplete slab of meniscal tissue with 80% coverage of the lateral tibial plateau. Am J Sports Med 2017; 45:884891, Zaffagnini S, Grassi A, Marcheggiani Muccioli GM, et al. 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 2008;191(1):81-5. The sagittal proton density-weighted image (2A) demonstrates increased signal intensity at the periphery of the medial meniscus posterior horn (arrow) but no fluid signal on the sagittal T2-weighted image (2B) and no gadolinium extension into this area on the MR arthrogram sagittal fat-suppressed T1-weighted arthrographic image (2C) consistent with a healed repair. The posterior root lies anterior to the posterior cruciate ligament. 2006;239(3):805-10. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. of the meniscus. incomplete breakdown of the central meniscus, but this is now disputed, Evaluation of postoperative menisci with MR arthrography and routine conventional MRI. 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. It can be divided into five segments: anterior horn, anterior, middle and posterior segments, and posterior horn. 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 anterior root of the lateral meniscus attaches to the tibia, just lateral to the midline and posterior to fibers of the anterior cruciate ligament (ACL). high fibula head and a widened lateral joint space.20 Several Lateral meniscus tears of the posterior root are a common concomitant injury to anterior cruciate ligament (ACL) tears [6, 16, 20]. medial meniscus, and not be confined to the ACL as seen in an ACL tear. bilaterally absent menisci reported by Tolo et al,3 the They often tend to be radial tears extending into the meniscal root. If missing on MR images, a posterior root tear is present. Diagnostic performance is decreased following partial meniscectomy since the standard criteria used to diagnose a meniscus tear cannot be applied to the post-operative meniscus.3,4,5,6 Partial meniscectomy may distort the normal morphology of the meniscus and increased meniscal signal intensity may extend to the articular surface when a portion of the meniscus has been resected, simulating a tear. The incidence was calculated based on arthroscopic findings, and the potential secondary signs of meniscal ramp tears were evaluated on MRI. The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. Total meniscectomy is rarely performed unless the meniscus is so severely damaged that no salvageable meniscal tissue remains. Zonal variation is also seen in the density of meniscus cells and their phenotypes with a chondrocytic inner zone and fibroblastic outer zone. Medial meniscus posterior horn peripheral longitudinal tear (arrow) seen on the sagittal proton density-weighted image (15A) and managed by repair. According to these authors, increased signal to the surface on only one slice should be interpreted as a possible tear. Cases of only one abnormal slice correlated to tears at arthroscopy 55 % of the time for the medial meniscus and 30 % for the lateral [, Accuracy of diagnosing meniscus tear with these criteria has been good. partly divides a joint cavity, unlike articular discs, which completely Most lateral meniscal tears are due to twisting or turning activities or falls. It has been calculated that the lateral meniscus absorbs about 70% of the forces across the lateral compartment of the knee. The ligament of Humphrey inserted on average 0.9 consecutive images lateral to the PCL without an PHLM tear and 4.7 with an PHLM tear; the ligament of Wrisberg inserted on average 3.0 consecutive images without an PHLM tear and 4.5 with an PHLM tear . Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. Meniscus repair is superior to partial meniscectomy in preventing osteoarthritis and facilitating return to athletic activity.11 However, the period of postoperative immobilization and activity restriction associated with meniscus repair is longer than that associated with partial meniscectomy and requires a compliant, motivated patient to be successful. anterior horn of the medial meniscus into the anterior cruciate ligament The most commonly practiced Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. proximal medial tibia was convex and the distal medial femoral condyle The most frequent symptom is pain that usually begins with a minor We use cookies to create a better experience. medial meniscus, discoid lateral meniscus, including the Wrisberg It is important to know the age of the patient when interpreting the MRI. These are like large radial tears and can destabilize a large portion of the meniscus. Criteria for a recurrent tear after greater than 25% meniscectomy Definite surfacing T2 fluid signal (or high T1 signal isointense to intra-articular gadolinium on MR arthrography) on 2 or more images or displaced meniscal fragment.17 Definite surfacing fluid signal on only one image represents a possible tear. The meniscal body is firmly attached to the deep portion of the medial collateral ligament complex via the meniscotibial ligament. The torn edges are aligned, and stable fixation applied with sutures or bioabsorbable implants at approximately 5 mm intervals. Menisci ensure normal function of the AJR American journal of roentgenology. Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG.
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