Pre-operative fat supressed coronal proton density-weighted image (19A) demonstates a posterior root radial tear (arrow). Heron, D, Bonnard C, Moraine C,Toutain A. Agenesis of cruciate You have reached your article limit for the month. 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. Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. posterior horn of the medial meniscus include a triangular hypointense 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 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. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. The ends of the anterior and posterior horns are firmly attached to the tibia at their roots. 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 On examination, there was marked medial joint line tenderness and a large effusion. in this case were attributed to an anterior cruciate ligament tear Discoid meniscus in children: Magnetic resonance imaging characteristics. does not normally occur.13. However, many clinicians opt to use conventional MRI as the initial postoperative imaging study and reserve MR arthrography for equivocal cases. medial meniscus are extremely uncommon and should not be a diagnostic 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 tear of the ACL should also, in practice, not be a 2008;191(1):81-5. A classification system developed by the International Society of Arthroscopy, Knee Surgery, and Orthopedic Sports Medicine [, Longitudinal-vertical tear. was saddle shaped. On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. Ideal for residents, practicing radiologists, and fellows alike, this updated reference offers easy-to-understand guidance on how to approach musculoskeletal MRI and recognize abnormalities. They found that 76 (8%) of these indicated a tear of the anterior horn of either the medial or lateral meniscus. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. 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. FSE T2-weighted images, with a slab-like appearance on coronal images. 3: The Wrisberg variant, where the meniscus may have a normal The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. We will review the common meniscal variants, which Nakajima T, Nabeshima Y, Fujii H, et al. A 2003 systematic review of the literature, in which 29 publications met strict inclusion criteria, demonstrated pooled weighted sensitivity and specificity of 93.3 % and 88.4 % for the medial meniscus and 79.3 % and 95.7 % for the lateral meniscus, respectively [, Most meniscal tears are visible and best seen on sagittal images. The articular cartilage is well seen on the pre-operative sagittal proton density-weighted image (19B). A preliminary report, Principles and decision making in meniscal surgery, The Anterior Meniscofemoral Ligament of the Medial Meniscus, Accurate patient history including site and duration of symptoms, Garrett WE Jr, Swiontkowski MF, Weinstein JN, et al. described in thrombocytopenia absent radius syndrome (TAR syndrome).2,3 Bilateral hypoplasia of the medial meniscus has also been reported.4. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). 2012;199(3):481-99. 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. A meta-analysis of 44 trials. Arthroscopy: The Journal of Arthroscopic & Related Surgery. meniscus. Am J Sports Med. snapping knee due to hypermobility. Discoid lateral meniscus (DLM) is a common anatomic variant in the knee typically presented in young populations, with a greater incidence in the Asian population than in other populations. However, clinically significant tears that can mechanically impinge were unlikely to have been missed. What is a Grade 3 meniscus tear? (as previously described), meniscal cyst,26 discoid lateral meniscus in the same knee (Figure 9),25 and pathologic medial patella plica.27. 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 . Report The reported prevalence is 0.06% to 0.3%.25 Clark CR, Ogden JA. Normal ligament and meniscal fascicles. An MRI of plaintiff's left knee conducted in May 2018 demonstrated a complex 7 tear of the posterior horn of the lateral meniscus and a suspected horizontal tear of the anterior horn of the lateral meniscus. Symptomatic anomalous insertion of the medial meniscus. 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. 3. If a meniscus tear shows up on a MRI, it is considered a Grade 3. History of medial meniscus posterior horn and body partial meniscectomy. MR criteria are used to make the diagnosis. Br Med Bull. The meniscal repair is intact. Surgical Outcomes Lysholm Score They are most frequently seen at the posterior horn of the medial meniscus. in 19916. an adult), and approximately twice the size of the anterior horn on Mechanical rasping or trephination of the torn meniscus ends and parameniscal synovium is used to promote bleeding and vascular healing. ; Lee, S.H. On this page: Article: Epidemiology Pathology Radiographic features History and etymology 4. On imaging alone, the radiologist may not be able to distinguish a residual tear (failed repair) from a recurrent tear in the same location. There are 3 main types, according to the Watanabe classification:18. The patient failed conservative management of aspiration and cortisone injection. The lateral meniscus is produced by the varus tension and tibial IR. Each meniscus attaches to the tibia bone in the back and front via the "meniscal roots." The primary role of the meniscus is to serve as a shock-absorber and protect the underlying articular cartilage and bone. There was no history of a specific knee injury. This is a critical differentiation because the latter represents meniscal tears that can be Fukuta S, Masaki K, Korai F. Prevalence of abnormal findings in magnetic resonance images of asymptomatic knees. 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. Lateral meniscus extrusion was present in six (23%) of 26 LMRTs and five (2.2%) of 231 patients with normal meniscus roots ( P < .001). 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. They were first described by M J Pagnaniet al. (PubMed: 17114506), BakerJC, FriedmanMV, RubinDA (2018) Imaging the postoperative knee meniscus: an evidence-based review. The trusted source for healthcare information and CONTINUING EDUCATION. A recurrent tear was proved at second look arthroscopy. 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. Menisci are present in the knees and the Meniscal disorders: Normal, discoid, and cysts. Pathology - a tear that has developed gradually in the meniscus. It is believed that discoid for the ratio of the sum of the width of the anterior and posterior proximal medial tibia was convex and the distal medial femoral condyle MRI has high sensitivity and specificity for detecting meniscus tears in patients without prior knee surgery. Most studies have shown increased accuracy for direct and indirect MR arthrography compared to conventional MRI for partial meniscectomies of 25% or more.16. 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. 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). It can be divided into five segments: anterior horn, anterior, middle and posterior segments, and posterior horn. diminutive (1 mm) with no increased signal to suggest root attachment 800-688-2421. Generally, AJR Am J Roentgenol. This is a well-done study with clinical correlation and adequate follow-up. of these meniscal variants is the discoid lateral meniscus, and the The example above demonstrates the importance of baseline MRI comparison when evaluating the postoperative meniscus. 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. They are usually due to an acute injury [. 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. The most widely used diagnostic modalities to assess the ligament injuries are arthroscopy and Magnetic Resonance Imaging (MRI). These tears are usually degenerative in nature and usually not associated with a discrete injury [. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. > 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% 1 ). A detached posterior root is functionally equivalent to a total meniscectomy with loss of its ability to withstand hoop stress. 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 . of the transverse ligament is comparable to the general population.5. When the cruciate The anterior and posterior sutures are shuttled down the tibial tunnel (arrowhead). ligaments and menisci causing severe knee dysplasia in TAR syndrome. The medial compartment articular cartilage is preserved, and the meniscal body is not significantly extruded (16D). instance, tears of the lateral aspect of the anterior horn of the 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. De Smet A. This case features the following signs of meniscal tear: Case courtesy, Prof. Dr. Khaled Matrawy, Professor of radiology, Alexandria university, Egypt. MRI Findings: Medial meniscus: Tear of the posterior horn seen to the inferior articular surface continuing into the posterior body and becoming more vertical. Meniscal transplants can fail at the implantation site by avulsion, failure of bone plug incorporation or bone bridge fracture. That reported case was also associated with If the tear does not show, it is considered a Grade 1 or 2 and is not as serious. The MRI revealed a vertical flap (oblique) tear of the medial meniscus. Posteroinferior displacement of the meniscal tissue (arrowheads) is also diagnostic of recurrent tear. 5. Torn lateral meniscus with superomedial and posterior flipped anterior horn. St. Louis County's newspaper of politics and culture Davidson D, Letts M, Glasgow R. Discoid meniscus in children: Treatment and outcome. The Wrisberg variant may present with a Best assessed on T2 weighted sequences. 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. 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. 2014; 43:10571064, McCauley TR. It affects 4% to 5% of the patient population,6-9 with a much higher incidence, up to 13%, in the Asian patient population.10 It is the most common meniscal variant in children.11 Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. Brody J, Lin H, Hulstyn M, Tung G. Lateral Meniscus Root Tear and Meniscus Extrusion with Anterior Cruciate Ligament Tear. 7 Therefore, it is important for the radiologist to be familiar with the appearance of a recurrent tear versus an untorn postoperative meniscus. Menisci ensure normal function of the Schwenke M, Singh M, Chow B Anterior Cruciate Ligament and Meniscal Tears: A Multi-modality Review. runs from the anterior horn of the medial meniscus to either the ACL or 2006; 187:W565568. acromioclavicular, sternoclavicular, and temporomandibular joints. The common insertion of the anterior cruciate ligament (ACL) and the AHLM root may provide a pathway for disease. MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. 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. The camera can visualize the meniscus and other structures within the knee. Because there is less pressure on the meniscus there, it is difficult to evaluate the anterior region of the meniscus. 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 [. 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. MRI: When you tear your meniscus, a magnetic resonance imaging (MRI) scan will show the injury as white lines on black. 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. Renew or update your current subscription to Applied Radiology. These features constitute O'Donoghue unhappy triad. Magnetic resonance imaging of the postoperative meniscus: resection, repair, and replacement. 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. Tear between 1-4 cm vertical tear red-red meniscal root <40 yo Maybe concominant ACL surgery . Each meniscus has three main parts, the back (posterior horn), middle (body), and front (anterior horn). 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. Of these 45 patients, there was an average of 3.74 additional pathological conditions noted on the MRI scan, mainly including degenerative arthrosis or patellar chondromalacia to explain the patients continued pain. of the Wrisberg ligament in patients with a complete lateral discoid 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. morphology. be misinterpreted for more significant pathology on MRI. Analytical, Diagnostic and Therapeutic Techniques and Equipment 13. This emphasizes the importance of meniscal repair over meniscectomy when possible and the need for meniscal preservation when a partial meniscectomy is necessary. When bilateral, they are usually symmetric. 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. An intact meniscal repair was confirmed at second look arthroscopy. 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 ]. The patient subsequently underwent successful partial medial meniscectomy. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. joint, and they also protect the hyaline cartilage. Repair devices including arrows, darts and sutures are used to approximate the torn edges of the meniscus. Radiology. Anatomic variability and increased signal change in this area are commonly mistaken for tears. Posterior meniscal root repairs: outcomes of an anatomic transtibial pull-out technique. to tear. 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. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). Sometimes T2 signal in a healed tear may look similar to fluid. A meniscal allograft transplant frequently leads to significant improvements in pain and activity level and hastens the return to sport for most amateur and professional athletes.13 A common method of meniscal allograft transplant includes a cadaveric meniscus (fresh or frozen) attached by its anterior and posterior roots to a bone bridge with a trapezoidal shape harvested from a donor tibia. This patient had relief after the initial repair surgery, then had a second injury with recurrent symptoms, which is why the surgeon felt this was a recurrent tear. In the U.S., intraarticular injection of gadolinium-based contrast is off label. 2006; 88:660667, Boutin RD, Fritz RC, Marder RA. Surgery is useful if they are unstable and flipping in and out of the joint causing pain. Medial meniscus posterior horn peripheral longitudinal tear treated with repair. These include looking for a Longitudinal medial meniscus tear managed by repair (arrow). On the sagittal proton density-weighted image (11A), signal contacts the tibial surface. Kaplan EB. 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 . 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? that this rare condition is also clinically asymptomatic. Illustration of the transtibial pullout repair for a tear of the posterior horn medial meniscal root (arrow). On MR arthrography, (12B), gadolinium extends through the repair site indicating a tear. Lateral meniscal variant with absence of the posterior coronary ligament. This emphasizes the importance of baseline MRI comparison for evaluation of the postoperative meniscus.3. The meniscus may also become hypertrophic. The patient had a recent new injury with increased pain. On MRI, they exhibit abnormal horizontal linear signal contacting the inferior articular surface near the free edge or less commonly the superior surface. This scan showed a radial MMT. Both the healed peripheral tear and the new central tear were proved at second look arthroscopy. The anterior meniscofemoral ligament (Humphrey ligament) attaches proximally on the medial femoral condyle, inferior to the PCL insertion. discoid lateral meniscus is a relatively uncommon developmental variant Normal course and intensity of both cruciate ligaments. The LaPrade classification systemof meniscal root tears has become commonly used in arthroscopy, and there is evidence that this system can be to some extent translated to MRI assessment of these tears ref. A Wrisberg type variant has not been documented in A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. The MRI revealed a longitudinal tear in the posterior horn of the lateral meniscus. is affected. Exam showed a mild effusion and medial joint line tenderness. These findings are also frequently associated with genu Clin Orthop Relat Res 2013; 471: pp. He presented after a few months with symptoms of instability. AJR American journal of roentgenology. 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. Following partial meniscectomy, the knee is at increased risk for osteoarthritis. 7.2 Medial and Lateral Menisci Medial meniscus is larger than the lateral meniscus and is more "open" (=less C-like) and less wide. In the previously reported cases, as well as in this case, the Radial Tear of the Medial Meniscal Root: Reliability and Accuracy of MRI for Diagnosis. 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. Lee S, Jee W, Kim J.