During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. These are like large radial tears and can destabilize a large portion of the meniscus. published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. asymptomatic, although there is a greater propensity for discoid menisci Torn lateral meniscus with superomedial and posterior flipped anterior horn. Associated anomalies in a discoid medial Damaged meniscal tissue is removed with arthroscopic instruments including scissors, baskets and mechanical shavers until a solid tissue rim is reached with the meniscal remnant contoured, preserving of as much meniscal tissue as possible. How I Diagnose Meniscal Tears on Knee MRI. 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 When interpreting MR images of the knee, it is important to assess for any change from the expected shape of the menisci. Kelly BT, Green DW. The Wrisberg variant may present with a {"url":"/signup-modal-props.json?lang=us"}, El-Feky M, Flipped meniscus - anterior horn lateral meniscus. Shepard et al have done a nice job of telling us just how frequently this mistake can be made by fellowship trained musculoskeletal radiologists. Increased signal intensity at the anterior horn of the lateral meniscus was seen on the images of seven of the 11 MR studies of the volunteers. And, some tears do not fill with contrast during arthrography. 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. horns to the meniscal diameter on a sagittal slice that shows a maximum The posterior horn is always larger than the anterior horn. The superior, middle and inferior geniculate arteries are the main vascular supply to the menisci. Copy. The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. Exam showed a mild effusion and medial joint line tenderness. described in thrombocytopenia absent radius syndrome (TAR syndrome).2,3 Bilateral hypoplasia of the medial meniscus has also been reported.4. Am J Sports Med 2016; 44:625632, De Smet AA, Horak DM, Davis KW, Choi JJ. MRI: When you tear your meniscus, a magnetic resonance imaging (MRI) scan will show the injury as white lines on black. 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. A Wrisberg type variant has not been documented in 15 year old patient with prior extensive lateral partial meniscectomy was treated with lateral chondroplasty and lateral meniscal allograft transplant with continued pain and clicking 6 weeks post-operative. When bilateral, they are usually symmetric. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. Congenital absence of the meniscus is extremely rare and has been documented in TAR syndrome and in isolated case reports.2,3 posterior horn of the medial meniscus include a triangular hypointense Discoid lateral meniscus in children. It is often explained by fibers of the anterior cruciate ligament and the covering synovium . If the tear does not show, it is considered a Grade 1 or 2 and is not as serious. Sagittal proton density-weighted image (7A) through the medial meniscus demonstrates increased signal extending to the tibial surface (arrow). The fat-suppressed sagittal T1-weighted post arthrogram view (7C) demonstrates gadolinium extending into the meniscal substance. It is located in the lateral portion of the knee interior of the knee joint. Synopsis: In a consecutive series of nearly 1000 knee MRIs, there was a 74% false-positive rate for the diagnosis of anterior horn meniscal tears. Intact meniscal roots. Complete radial tears, root tears and large partial meniscectomies result in markedly increased contact forces at the articular surface; and in this case, full-thickness chondral loss and subchondral fractures on both sides of the joint. Discoid lateral meniscus and the frequency of meniscal tears. 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. Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). and ACL tears can be mistaken for AIMM, but carefully tracing the The articular cartilage is well seen on the pre-operative sagittal proton density-weighted image (19B). Skeletal radiology. The patient underwent partial medial meniscectomy and ACL reconstruction. What is a Lateral Meniscus Tear? Best assessed on T2 weighted sequences. Fellowship-trained musculoskeletal radiologists read 99% of the MRIs. Report My own experience has been similar and I make it a policy not to recommend surgery based on this diagnosis alone without good clinical correlation. Repair devices including arrows, darts and sutures are used to approximate the torn edges of the 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). Am J Sports Med 2017; 45:4249, ElAttar M, Dhollander A, Verdonk R, Almqvist KF, Verdonk P. Twenty six years of meniscal allograft transplantation: is it still experimental? American Board of Orthopaedic Surgery Practice of the Orthopaedic Surgeon: Part-II, certification examination case mix. with mechanical features of clicking and locking. congenital absence of the cruciate ligaments. On examination, there was marked medial joint line tenderness and a large effusion. The main functions Indications for meniscal repair typically include posttraumatic peripheral (red zone) longitudinal tears located near the joint capsule, ideally in younger patients (less than 40). Anatomic variability and increased signal change in this area are commonly mistaken for tears. Type 1: A complete slab of meniscal tissue with complete tibial coverage. There is a medial and a lateral meniscus. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). Concise, to-the-point text covers MRI for the entire musculoskeletal system, presented in a highly templated format. Magnetic resonance imaging (MRI) is the most accurate imaging technique in the diagnosis of meniscal lesions and represents a standard tool in knee evaluation. We look forward to having you as a long-term member of the Relias Type Congenital discoid cartilage. 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. The medial compartment articular cartilage is preserved, and the meniscal body is not significantly extruded (16D). Lee, J.W. Radial Tear of the Medial Meniscal Root: Reliability and Accuracy of MRI for Diagnosis. Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG. Radiology. 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. 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. Each meniscus has three main parts, the back (posterior horn), middle (body), and front (anterior horn). Rao PS, Rao SK, Paul R. Clinical, radiologic, and arthroscopic assessment of discoid lateral meniscus. The tear was treated by partial meniscectomy at second surgery. treatment for stable complete or incomplete types of discoid lateral Disadvantages include risks associated with joint injection, radiation exposure and lower contrast resolution compared to MRI, particularly in the extraarticular soft tissues. 1 ). MR criteria for discoid lateral menisci are used for discoid medial 2006; 187:W565568. Choi S, Bae S, Ji S, Chang M. The MRI Findings of Meniscal Root Tear of the Medial Meniscus: Emphasis on Coronal, Sagittal and Axial Images. 4. The lateral meniscus is one of two fibrocartilaginous menisci of the knee. Among these 26 studies of an LMRT . acromioclavicular, sternoclavicular, and temporomandibular joints. Absence of the meniscus results in a 200 to 300% increase in contact stresses on the articular surfaces.8The meniscus has a heterogeneous cellular composition with regional and zonal variation, with high proteoglycan content at the thin free edge where compressive forces predominate and low proteoglycan content at the thicker peripheral region where circumferential tensile loads predominate. They may not even be apparent with an arthroscopic examination. AJR Am J Roentgenol. proximal medial tibia was convex and the distal medial femoral condyle Sometimes T2 signal in a healed tear may look similar to fluid. It is believed that discoid ligaments and menisci causing severe knee dysplasia in TAR syndrome. Definite surfacing signal or distortion on only one image represents a possible tear. 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. They often tend to be radial tears extending into the meniscal root. At the time the article was last revised Yahya Baba had 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. Radial tears comprise approximately 15 % of tears in some surgical series [. The anterior meniscofemoral ligament (Humphrey ligament) attaches proximally on the medial femoral condyle, inferior to the PCL insertion. Cho JM, Suh JS, Na JB, et al. Clin Orthop Relat Res 2013; 471: pp. When the cruciate Relevant clinical history, prior imaging and use of operative reports will significantly improve accuracy of post-operative interpretations. small meniscus is also seen in the wrist joint. For DSR inquiries or complaints, please reach out to Wes Vaux, Data Privacy Officer, Kijowski et al. 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. Tears One important reason for such discrepancies is a failure to understand the transverse geniculate ligament of the knee (TGL). 3. diminutive (1 mm) with no increased signal to suggest root attachment The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. If a horizontal tear involves a long segment of the meniscus, the central fragment may displace centrally from the peripheral portion of the meniscus [, Bucket handle tears (BHT) often cause pain and mechanical symptoms, such as locking, catching, and giving way [. The purpose of our study was to determine if cysts of the ACL are the origin of cysts adjacent to the AHLM. Continuous meniscal tissue bridged the anterior and posterior horns of the lateral meniscus on 3 consecutive sagittal slices (Figure 1B). In The anomalous insertion Conventional MRI is the least invasive modality for evaluation of a meniscal repair but has lower sensitivity, specificity and accuracy than direct or indirect arthrographic MRI. On the fat-supressed proton density-weighted coronal (17A) and axial (17B) images, notice the trapazoidal shaped bone bridge (arrow) placed in the tibial slot with menscal allograft attached at the anterior and posterior roots. Menisci ensure normal function of the 5. A recurrent tear was proved at second look arthroscopy. Meniscal disorders: Normal, discoid, and cysts. slab-like configuration on sagittal MR images, with > 3 bowties Indications for a partial meniscectomy include meniscal tears not amenable to repair which includes non-peripheral tears with a horizontal, oblique or complex tear pattern and nontraumatic tears in older patients. The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. If missing on MR images, a posterior root tear is present. MRI of the knee is commonly indicated for evaluation of unresolved or recurrent knee pain following meniscal surgery. Discoid medial meniscus. FSE T2-weighted images, with a slab-like appearance on coronal images. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. Intensity of signal contacting meniscal surface in recurrent tears on MR arthrography compared with that of contrast material. | 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. an adult), and approximately twice the size of the anterior horn on 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. Connolly B, Babyn PS, Wright JG, Thorner PS. in 19916. Normal course and intensity of both cruciate ligaments. bilaterally absent menisci reported by Tolo et al,3 the 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. No meniscal tear is seen, but the root attachment was also noted to be intra-articular structures at 8 weeks gestation. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. Tears in the red zone have the potential to heal and are more amenable to repair. gestation, about the time when the knee joint is fully formed.1 Throughout fetal development, they found that the size of the lateral meniscus is highly variable, unlike the medial meniscus. At least one meniscofemoral ligament is present in 7093 % Of knees The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. 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 A tear of the meniscal root means the tear is near where it attaches to the bone, usually far in the back. 2059-2066, Kinsella S.D., and Carey J.L. Monllau J, Gonzalez G, Puig L, Caceres E. Bilateral hypoplasia of the medial meniscus. 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. The example above demonstrates the importance of baseline MRI comparison when evaluating the postoperative meniscus. At second look arthroscopy, the posterior horn tear was healed and the anterior horn tear was found to be unstable and treated by partial meniscectomy. morphology. On this page: Article: Epidemiology Pathology Radiographic features History and etymology tear. Thus, the loss of the lateral meniscus can often lead to rather rapid onset of osteoarthritis. found that the absence of a line of increased signal through the meniscus extending to the articular surface on proton density and T2-weighted images was a reliable MRI finding for an untorn post-operative meniscus with 100% sensitivity. It is usually seen near the lateral meniscus central attachment site. . Also, the inferior patella plica inserts on the show cupping of the medial tibial plateau, proximal medial tibial physis anterior horn of the medial meniscus into the anterior cruciate ligament On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. It is possible that there could have been some tears missed at arthroscopy that were on the undersurface of the anterior horn, an area which is extremely difficultif not impossibleto visualize. The location of meniscal tears or signal alterations (anterior/posterior horn or body of the medial/lateral meniscus) and the grade (normal/intra-substance signal abnormality = 0 and tear = 1) were determined on 2D . mobility, and a giving-way sensation.11, 15, 16 A high percentage of cases present with an associated meniscal tear and peripheral rim instability.9,16,17 Although discoid lateral meniscus is commonly bilateral, symptoms tend to occur on one side.15 It is characterized by an excess of meniscal tissue with a slab-like configuration in the 2 most common forms (Figure 5). appearance.12 It is now believed that the knee develops from a sagittal magnetic resonance (MR) images. 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. Renew or update your current subscription to Applied Radiology. Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. Sagittal proton density (PD) images through normal medial (, The medial meniscus is larger, more oblong, and normally has a larger posterior horn than anterior horn in cross section. Special thanks to David Rubin, MD for providing several cases used in this web clinic. Close clinical correlation is advised before recommending surgery based on this finding alone. The medial meniscus is asymmetrical with a larger posterior horn. Both ligaments attach distally to the posterior horn of the lateral meniscus and contribute to posterior drawer stability . Problems encountered in a discoid medial meniscus are the same as a Case study, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-75066. Become a Gold Supporter and see no third-party ads. After failing conservative management with NSAIDs, PT, and activity modification, he underwent an MRI. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. The meniscus is diffusely vascularized in early life but in adults, only 10-30% of the peripheral meniscus is vascularized, often referred to as the red zone. We hope you found our articles 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. The incidence was calculated based on arthroscopic findings, and the potential secondary signs of meniscal ramp tears were evaluated on MRI. Posterior root repair (Figure 16) is being performed with increasing frequency and has been shown to have better outcomes and decreased risk of osteoarthritis compared to posterior root tears treated non-operatively.
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