Bilateral hypoplasia of the medial meniscus has also been posterior horn of the medial meniscus include a triangular hypointense Sagittal proton density-weighted image (6A) through the medial meniscus following partial meniscectomy and debridement of the inferior articular surface shows increased PD signal contacting the inferior articular surface (arrow) but no T2 fluid signal at the surgical site (6B) and no gadolinium signal in the meniscus (6C). The ends of the anterior and posterior horns are firmly attached to the tibia at their roots. > 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% When the cruciate 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. The most widely used diagnostic modalities to assess the ligament injuries are arthroscopy and Magnetic Resonance Imaging (MRI). At 1 year, 5 of 6 were completely asymptomatic with the remaining patient minimally painful with no suggestion of meniscal symptoms. In these cases, surfacing meniscal signal on low TE series may represent recurrent tear, granulation tissue or residual grade 2 degenerative signal that contacts the meniscal surface after debridement. occur with minor trauma. At least one meniscofemoral ligament is present in 7093 % Of knees Thus, the loss of the lateral meniscus can often lead to rather rapid onset of osteoarthritis. structure on sagittal images on T1, proton density, and fat-saturated The knee is a complex synovial joint that can be affected by a range of pathologies: ADVERTISEMENT: Supporters see fewer/no ads, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 1). For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign. Report 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 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). 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 . normal knee. 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. An intact meniscal repair was confirmed at second look arthroscopy. 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. Anatomic variability and increased signal change in this area are commonly mistaken for tears. medial meniscus, and not be confined to the ACL as seen in an ACL tear. trauma; however, other symptoms include clicking, snapping, and locking Discoid meniscus in children: Magnetic resonance imaging characteristics. However, many clinicians opt to use conventional MRI as the initial postoperative imaging study and reserve MR arthrography for equivocal cases. 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. On examination, the patient had medial joint line tenderness with positive McMurray test. Recent evidence suggests that decreased extrusion may correlate to better clinical outcomes.18. 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. Diagnosis - clinical presentation with exclusion of advanced knee osteoarthritis. Arthroscopy evaluation found a lateral meniscus peripheral (red-white zone) longitudinal tear. This case features the following signs of meniscal tear: Case courtesy, Prof. Dr. Khaled Matrawy, Professor of radiology, Alexandria university, Egypt. These findings are also frequently associated with genu It is often explained by fibers of the anterior cruciate ligament and the covering synovium . congenital anomalies affect the lateral meniscus, most commonly a 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. Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG. 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. 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. 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 [. On MRI, they exhibit abnormal horizontal linear signal contacting the inferior articular surface near the free edge or less commonly the superior surface. 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 History of a longitudinal medial meniscus tear managed by repair and concurrent ACL reconstruction. A classification system developed by the International Society of Arthroscopy, Knee Surgery, and Orthopedic Sports Medicine [, Longitudinal-vertical tear. Of these patients treated nonoperatively, 6 had a diagnosis of an isolated anterior horn tear on MRI. At the time the article was last revised Yahya Baba had When bilateral, they are usually symmetric. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. 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. Resnick D, Goergen TG, Kaye JJ, et al. The tear was treated by partial meniscectomy at second surgery. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. Additionally, the postoperative complication of new extensive synovitis is apparent on the axial view (18D). Anterior lateral cysts extended . intra-articular structures at 8 weeks gestation. reported.4. Advantages include a less invasive method of introducing intraarticular contrast, the ability to identify areas of hyperemic synovitis or periarticular inflammation based on enhancement and administration can be performed by the technologist. This case features the following signs of meniscal tear: absent bow tie appearance of the lateral meniscus ghost meniscus: empty location of the anterior horn of the lateral meniscus The trusted source for healthcare information and CONTINUING EDUCATION. 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. Symptoms of anterior horn tears were very similar to those of meniscal tears of the midbody or posterior horn, including catching, pain with knee flexion, and swelling. 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. the intercondylar notch, most commonly to the mid ACL, and less commonly The example above illustrates marked degenerative changes caused by loss of meniscal function. an adult), and approximately twice the size of the anterior horn on ligament will help to exclude these conditions.5 In the first Disadvantages include risks associated with joint injection, radiation exposure and lower contrast resolution compared to MRI, particularly in the extraarticular soft tissues. 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. Magnetic resonance imaging (MRI) of both knee joints showed an almost complete absence of the anterior and posterior horns of the medial meniscus, except for the peripheral portion, hypoplastic anterior horns and tears in the posterior horns of the lateral meniscus in both knees (Fig. However, clinically significant tears that can mechanically impinge were unlikely to have been missed. 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. Discoid lateral meniscus in children. The condition is typically asymptomatic and, therefore, is infrequently diagnosed.14 to tear. A meta-analysis of 44 trials. 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. Discoid medial menisci are much less common than discoid lateral menisci,24 and they may be bilateral. Lateral Meniscus: Anatomy The lateral meniscus is seen as a symmetric bow tie in the sagittal plane on at least one or two sections before it divides into two asymmetric triangles near the midline. Normal Kijowski et al. treatment for stable complete or incomplete types of discoid lateral Medial meniscus bucket handle tears can result in a double PCL sign. Most horizontal tears extend to the inferior articular surface. The anterior and posterior sutures are shuttled down the tibial tunnel (arrowhead). Unable to process the form. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. A 510, 210-pound 16-year-old male injured his left knee while kicking a football. This is a well-done study with clinical correlation and adequate follow-up. 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. As DLM is a congenital anomaly, the ultrastructural features and morphology differ from those of the normal meniscus, potentially leading to meniscal tears. Findings indicate an intact meniscus following partial meniscectomy with normal intrameniscal signal. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. Lee S, Jee W, Kim J. Regardless of the imaging protocol chosen for evaluation of the postoperative meniscus, optimal imaging interpretation includes: The normal MRI appearance after partial meniscectomy is volume loss and morphologic change, commonly truncation or blunting of the meniscal free edge. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. Monllau J, Gonzalez G, Puig L, Caceres E. Bilateral hypoplasia of the medial meniscus. 800-688-2421. According to one source, they are thought to account for ~10% of all arthroscopic meniscectomies 5. 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. attachment of the posterior horn is the Wrisberg meniscofemoral Type 1: A complete slab of meniscal tissue with complete tibial coverage. 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. Kijowski et al. Brody J, Lin H, Hulstyn M, Tung G. Lateral Meniscus Root Tear and Meniscus Extrusion with Anterior Cruciate Ligament Tear. . A 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 rare ring-shaped meniscus, to the classification. Media community. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. Repair devices including arrows, darts and sutures are used to approximate the torn edges of the meniscus. They maintain a relatively constant distance from the periphery of the meniscus [. Examination showed lateral joint line tenderness and a positive McMurray sign. Long-term outcome after arthroscopic meniscal repair versus arthroscopic partial meniscectomy for traumatic meniscal tears. 300). of the Wrisberg ligament in patients with a complete lateral discoid discoid lateral meniscus, including a propensity for tears to occur and Fat suppressed sagittal T1-weighted MR arthrogram (5C) demonstrates gadolinium within the tear (arrow). Definite surfacing signal or distortion on only one image represents a possible tear. was saddle shaped. Problems encountered in a discoid medial meniscus are the same as a 10 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 medial meniscus is more tightly anchored than the lateral meniscus, allowing for approximately 5mm of anterior-posterior translation. variant, and discoid medial meniscus. There was no history of a specific knee injury. no specific MR criteria for classifying discoid medial menisci, and the Continuous meniscal tissue bridged the anterior and posterior horns of the lateral meniscus on 3 consecutive sagittal slices (Figure 1B). In this case, we can determine that there is a new tear in a different location. 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. MR imaging is useful for evaluation of many possible complications following meniscal surgery. No paralabral cyst. Of the 14 athletes, 8 repairs were performed, 5 patients . In contrast to the medial meniscus, the posterior horn of the lateral meniscus is additionally secured by the meniscofemoral ligaments (MFL). 2020;49(1):42-49. as at no time in development does the meniscus have a discoid Samoto N, Kozuma M, Tokuhisa T, Kobayashi K. Diagnosis of discoid lateral meniscus of the knee on MR imaging. ligaments and menisci causing severe knee dysplasia in TAR syndrome. A tear of the ACL should also, in practice, not be a incomplete breakdown of the central meniscus, but this is now disputed, 4). Magn Reson Imaging Clin N Am 2014;22(4): 517555, White LM, Schweitzer ME, Weishaupt D, Kramer J, Davis A, Marks PH. History of longitudinal medial meniscus tear managed by meniscal repair (arrows). Congenital absence of the meniscus is extremely rare and has been documented in TAR syndrome and in isolated case reports.2,3 Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). snapping knee due to hypermobility. 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. The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. Their 74% false-positive rate I believe is accurate and one that we can incorporate mentally into our practice as we evaluate patients and the MRI scan results. To provide the highest quality clinical and technology services to customers and patients, in the spirit of continuous improvement and innovation. Torn lateral meniscus with superomedial and posterior flipped anterior horn. horns to the meniscal diameter on a sagittal slice that shows a maximum They may not even be apparent with an arthroscopic examination. 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. For partial meniscectomies involving 25% or more, conventional MRI has lower accuracy. 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. the medial meniscus. MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. Youderian A, Chmell S, Stull MA. 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. The MRI also demonstrated moderate degenerative spurring at the lateral joint compartment, a large knee joint effusion with . The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. . Reference article, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-40036, {"containerId":"expandableQuestionsContainer","displayRelatedArticles":true,"displayNextQuestion":true,"displaySkipQuestion":true,"articleId":40036,"questionManager":null,"mcqUrl":"https://radiopaedia.org/articles/meniscal-root-tear/questions/1112?lang=us"}. A 64-year-old female with no specific injury presented with knee pain, swelling, and locking that she first noticed after working out at the gym. History of medial meniscus posterior horn and body partial meniscectomy. On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. The shape of the meniscus is formed at the eighth week of meniscus is partial meniscal excision, leaving a 6- to 7-mm peripheral A previous study by De Smet et al. Sagittal T2-weighted (16A), fat-suppressed proton density-weighted sagittal (16B) and coronal (16C, D) images demonstrate findings of a posterior root transtibial pullout repair with visualization of the tibial tunnel (arrow), susceptibility artifact caused by the endobutton (asterisk) and fraying of the posterior root (arrowhead) but no tear. In the above case there is no gross chondral defect although the articular cartilage is noticeably thinner compared to the baseline study despite the patients young age. Stein T, Mehling AP, Welsch F, von EisenhartRothe R, Jger A. The posterior cruciate ligament is intact. The patient subsequently underwent successful partial medial meniscectomy. Congenital discoid cartilage. 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 ]. 2012;199(3):481-99. The posterior root of the lateral meniscus (PRLM) attaches along the posterior aspect of the intercondylar eminence of the tibia (Fig. (Figure 1). meniscal diameter. Figure 7: Meniscofemoral ligament. On sagittal proton-density and T2-weighted images, this lesion was demonstrated by sensitive but nonspecific signs, such as the flipped meniscus . Grade 3 is a true meniscus tear and an arthroscope is close to 100 percent accurate in diagnosing this tear. Intact meniscal roots. They often tend to be radial tears extending into the meniscal root. 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.
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