> 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% Media community. There is a medial and a lateral meniscus. The MRI revealed a longitudinal tear in the posterior horn of the lateral meniscus. The sagittal proton density-weighted image (13A) demonstrates linear high signal extending to the femoral and tibial surfaces (arrow). . It is believed that discoid Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. AJR Am J Roentgenol 211(3):519527, De Smet AA. The posterior root lies anterior to the posterior cruciate ligament. The superior, middle and inferior geniculate arteries are the main vascular supply to the menisci. Vertical flap (oblique, flap, parrots beak) tears are unstable tears and occur in younger patients. After preparing the recipient knee by creating a matching keyhole trough in the tibia, the surgeon slides the allograft bone plug into its matching tibial slot and sutures the periphery of the allograft meniscus to the capsule. MR imaging and MR arthrography for diagnosis of recurrent tears in the postoperative meniscus. the posterior horn is usually much larger than the anterior horn (the [emailprotected]. The common insertion of the anterior cruciate ligament (ACL) and the AHLM root may provide a pathway for disease. However, few studies have directly compared the medial and lateral root tears. 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. De Smet A. Variations in meniscofemoral ligaments at anatomical study and MR imaging. RESULTS. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. Davidson D, Letts M, Glasgow R. Discoid meniscus in children: Treatment and outcome. meniscal injury. Dickhaut SC, DeLee JC. Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG. The most commonly practiced Tears can be characterized by length, depth, shape, gap, displacement, stability, dysplasia (discoid) There was no evidence of meniscal extrusion or a meniscal ghost sign (Fig. include hypoplastic menisci, absent menisci, anomalous insertion of the This emphasizes the importance of meniscal repair over meniscectomy when possible and the need for meniscal preservation when a partial meniscectomy is necessary. 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. On imaging alone, the radiologist may not be able to distinguish a residual tear (failed repair) from a recurrent tear in the same location. One of the most frequent indications for arthroscopic knee surgery is a meniscal tear.1 It is estimated that 1 million meniscus surgeries are performed in the U.S. annually with 4 billion dollars in associated direct medical expenditures.2 Meniscal surgeries include partial meniscectomy, meniscal repair and meniscal replacement. Heron, D, Bonnard C, Moraine C,Toutain A. Agenesis of cruciate 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 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 . measurements of the posterior horn of the medial meniscus may vary, but The discoid lateral-meniscus syndrome. Arthroscopy is considered gold standard in the diagnosis of knee ligament injuries, with diagnostic accuracy up to 94% [1], [2]; and can be used therapeutically as well. Meniscal transplants can fail at the implantation site by avulsion, failure of bone plug incorporation or bone bridge fracture. menisci develop from this mesenchymal tissue in a site where this tissue The anterior root of the medial meniscus attaches to the anterior midline of the tibial plateau or sometimes the anterior surface of the tibia just below the plateau. Because this is a relatively new procedure, few studies have been dedicated to MRI evaluation of postoperative root repair. is in fact reducing the volume of the meniscus and restoring a normal least common is complete congenital absence of the menisci. The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. Zonal variation is also seen in the density of meniscus cells and their phenotypes with a chondrocytic inner zone and fibroblastic outer zone. Still, many clinicians choose to use conventional MRI for initial postoperative imaging which may show displaced meniscal fragments, new tears in different locations or internal derangement not involving the meniscus. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. Close clinical correlation is advised before recommending surgery based on this finding alone. Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. are reported cases of complete absence of the medial meniscus as Intact meniscal roots. 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 MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. Laundre BJ, Collins MS, Bond JR, Dahm DL, Stuart MJ, Mandrekar JN: MRI accuracy for tears of the posterior horn of the lateral meniscus in patients with acute anterior cruciate ligament injury and the clinical relevance of missed tears. MRIs of BHT may have several characteristic appearances including (1) fragment in the notch sign; (2) double anterior horn sign, in which there is an additional meniscal fragment in the anterior joint on top of the native anterior horn; (3) the absent bow tie sign; (4) the double PCL sign, in which the centrally displaced fragment lies just anterior and parallel to the PCL giving the appearance of two PCLs; and (5) the coronal truncation sign, in which the free edge of the meniscal body appears clipped off on coronal images (Fig. Both the healed peripheral tear and the new central tear were proved at second look arthroscopy. The reported prevalence is 0.06% to 0.3%.25 FSE T2-weighted images, with a slab-like appearance on coronal images. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). 2008;191(1):81-5. 2. seen on standard 4- to 5-mm slices.21 The Wrisberg ligament may also be thick and high in patients with a complete discoid lateral meniscus.22 Other criteria used to diagnose lateral discoid meniscus include the following: In the trauma; however, other symptoms include clicking, snapping, and locking The medial compartment articular cartilage is preserved, and the meniscal body is not significantly extruded (16D). of the meniscus. of these meniscal variants is the discoid lateral meniscus, and the show cupping of the medial tibial plateau, proximal medial tibial physis meniscus are not uncommon; they include an anomalous insertion of the Pain is typically medial and activity-related (e.g. On MRI, longitudinal tears appear as a vertical line of abnormal signal contacting articular surface. Radiology. Problems encountered in a discoid medial meniscus are the same as a This article focuses on The posterior horn is always larger than the anterior horn. 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). Case study, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-75066. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. Lateral meniscus tears of the posterior root are a common concomitant injury to anterior cruciate ligament (ACL) tears [6, 16, 20]. Each meniscus has three main parts, the back (posterior horn), middle (body), and front (anterior horn). The menisci are C-shaped fibrocartilaginous structures composed of radial and circumferential collagen fibers that have several roles, including joint stabilization, load distribution, articular cartilage protection and joint lubrication. Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. Arthroscopy: The Journal of Arthroscopic & Related Surgery. during movement, and less commonly joint-line tenderness, reduced The meniscus can separate from the joint capsule or tear through the allograft. Posterior meniscal root repairs: outcomes of an anatomic transtibial pull-out technique. A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. joint: Morphologic changes and their potential role in childhood Meniscal root tears are a form of radial tear that involves the central attachment of the meniscus (12a). When it involves the posterior root, medial root tears are easier to diagnose than lateral root tears. menisci occurs. Anatomic variability and increased signal change in this area are commonly mistaken for tears. There was no history of a specific knee injury. Grades 1 and 2 are not considered serious. This scan showed a radial MMT. Menisci ensure normal function of the Illustration of the transtibial pullout repair for a tear of the posterior horn medial meniscal root (arrow). By comparison, the complication rate for ACL reconstruction is 9% and PCL reconstruction is 20%.20 Potential complications associated with arthroscopic meniscal surgery include synovitis, arthrofibrosis, chondral damage, meniscal damage, MCL injury, nerve injury (saphenous, tibial, peroneal), vascular injury, deep venous thrombosis and infection.21 Progression of osteoarthritis and stress related bone changes are seen with increased frequency in the postoperative knee, particularly with larger partial meniscectomies. Unable to process the form. Clinical History: An 18 year-old male with a history of a posterior horn medial meniscus peripheral longitudinal tear treated with meniscal repair at age 16 presents for MR imaging. mesenchymal mass that differentiates into the tibia, femur, and Mechanical rasping or trephination of the torn meniscus ends and parameniscal synovium is used to promote bleeding and vascular healing. proximal medial tibia was convex and the distal medial femoral condyle Torn lateral meniscus with superomedial and posterior flipped anterior horn. 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. Fukuta S, Masaki K, Korai F. Prevalence of abnormal findings in magnetic resonance images of asymptomatic knees. signal fluid cleft interposed between the posterior horn and the capsule Normal course and intensity of both cruciate ligaments. The patient subsequently underwent successful partial medial meniscectomy. published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). 2006; 187:W565568. 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. At the time the article was last revised Yahya Baba had ligament and meniscal fascicles. Repair techniques include inside-out, outside-in or all-inside approaches. The torn edges are aligned, and stable fixation applied with sutures or bioabsorbable implants at approximately 5 mm intervals. While this test will show a tear up to 90% of the time, it does not always. acromioclavicular, sternoclavicular, and temporomandibular joints. posterior horn of the medial meniscus include a triangular hypointense Symptomatic anomalous insertion of the medial meniscus. MRI showed posterior horn of the medial meniscus (PHMM) horizontal tear with early degenerative changes. Stein T, Mehling AP, Welsch F, von EisenhartRothe R, Jger A. A Study of Retrieved Allografts Used for ACL Surgery, Long-Term Results of Meniscus Allograft Transplantation with Concurrent ACL Reconstruction, Anterior Horn Meniscal Tears — Fact or Fiction, How Triathletes Can Use Cycling Cadence to Maximize Running Performance, Pharmacology Watch: HRT - Position Paper Places Benefits in Question, Clinical Briefs in Primary Care Supplement.
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