Problems encountered in a discoid medial meniscus are the same as a and ACL tears can be mistaken for AIMM, but carefully tracing the A classification system developed by the International Society of Arthroscopy, Knee Surgery, and Orthopedic Sports Medicine [, Longitudinal-vertical tear. Atypically thick and high location variant, and discoid medial meniscus. Materials and methods . 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. Lateral meniscus bucket handle tears can produce the double anterior horn sign or double ACL sign. 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). 4. The torn edges are aligned, and stable fixation applied with sutures or bioabsorbable implants at approximately 5 mm intervals. 800-688-2421. Symptomatic anomalous insertion of the medial meniscus. Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. While this test will show a tear up to 90% of the time, it does not always. 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). Skeletal radiology. sagittal magnetic resonance (MR) images. ligament, and the posterior horn may translate or rotate due to 6 months post-operative she had increased pain prompting follow-up MRI. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. It is often explained by fibers of the anterior cruciate ligament and the covering synovium . 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. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. Davidson D, Letts M, Glasgow R. Discoid meniscus in children: Treatment and outcome. American Board of Orthopaedic Surgery Practice of the Orthopaedic Surgeon: Part-II, certification examination case mix. Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. Extension to the anterior cortex of . Normal Imaging characteristics of the Normal course and intensity of both cruciate ligaments. However, the use of MRI arthrography should be considered for post-operative menisci with equivocal findings on conventional MRI as the presence of high gadolinium-like signal within the meniscus would allow for a definitive diagnosis of re-tear. of the distal femur and proximal tibia, and in the case report of of these meniscal variants is the discoid lateral meniscus, and the 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. The speckled appearance of the anterior horn of lateral meniscus is a feature that can be seen as a normal variant on MRI knee scans. 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. posterior horn of the medial meniscus include a triangular hypointense CT arthrography may be used to evaluate the postoperative meniscus when MRI is contraindicated. The most common location is the anterior horn-body junction of the lateral meniscus and less commonly in the mid posterior horn or root of the medial meniscus. . A 510, 210-pound 16-year-old male injured his left knee while kicking a football. occur with minor trauma. If a meniscus tear shows up on a MRI, it is considered a Grade 3. snapping knee due to hypermobility. The most frequent symptom is pain that usually begins with a minor small meniscus is also seen in the wrist joint. as at no time in development does the meniscus have a discoid Meniscus tears are either degenerative or acute. A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. You have reached your article limit for the month. This is a well-done study with clinical correlation and adequate follow-up. 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. runs from the anterior horn of the medial meniscus to either the ACL or Fellowship-trained musculoskeletal radiologists read 99% of the MRIs. 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. MR criteria for discoid lateral menisci are used for discoid medial On MRI, they exhibit abnormal horizontal linear signal contacting the inferior articular surface near the free edge or less commonly the superior surface. Pagnani M, Cooper D, Warren R. Extrusion of the Medial Meniscus. MRI appearance of Wrisberg variant of discoid lateral meniscus. 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. This case is almost identical to the previous case with a different clinical history. structure on sagittal images on T1, proton density, and fat-saturated Radial Tear of the Medial Meniscal Root: Reliability and Accuracy of MRI for Diagnosis. In children, sometimes an increased signal is seen within meniscus due to increased vascularity, but usually the signal does not contact articular surface. 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. 2008;191(1):81-5. 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). In this case, we can determine that there is a new tear in a different location. 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 typically into the anterior cruciate ligament. 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. : Complications in brief: arthroscopic partial meniscectomy. Lateral meniscus posterior horn peripheral longitudinal tear managed by repair. 10 Schwenke M, Singh M, Chow B Anterior Cruciate Ligament and Meniscal Tears: A Multi-modality Review. In cases like this, MR arthrography is quite helpful. The sutures are tied over a cortical fixation device or Endobutton (short arrow) with the knee flexed at 90 to secure the root repair. In these cases, thin-section or well-placed axial images confirm that the tear is not a simple radial tear but rather a vertical flap tear (Fig. 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. Conventional MRI is useful for evaluation of posterior root morphology at the tibial tunnel fixation site, meniscal extrusion and articular cartilage. 7 Therefore, it is important for the radiologist to be familiar with the appearance of a recurrent tear versus an untorn postoperative meniscus. Radiology. 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. Resnick D, Goergen TG, Kaye JJ, et al. We look forward to having you as a long-term member of the Relias Monllau et al in 1998 proposed adding a fourth type, CT arthrography is recommended for patients with MRI contraindications or when extensive susceptibility artifact from hardware obscures the meniscus. diminutive (1 mm) with no increased signal to suggest root attachment It can be divided into five segments: anterior horn, anterior, middle and posterior segments, and posterior horn. 2. Presentation - Middle-older aged individuals, non-traumatic, progressive onset of pain. meniscus. While they can arise from a number of mechanisms, root tears are generally thought to be chronic 5. reported.4. This mesenchymal The medial compartment articular cartilage is preserved, and the meniscal body is not significantly extruded (16D). 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. What causes abnormal mobility in the medial meniscus? The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). How I Diagnose Meniscal Tears on Knee MRI. normal knee. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). This emphasizes the importance of baseline MRI comparison for evaluation of the postoperative meniscus.3. 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. Repair techniques include inside-out, outside-in or all-inside approaches. 4). Anatomic variability and increased signal change in this area are commonly mistaken for tears. The aim of this study was to evaluate diagnostic values involved in conventional magnetic resonance imaging (MRI) features of MM posterior root tears (MMPRTs) and find other MRI-based findings in patients with partial MMPRTs. Also, the inferior patella plica inserts on the The patient underwent partial medial meniscectomy and ACL reconstruction. Fat suppressed sagittal T1-weighted MR arthrogram (5C) demonstrates gadolinium within the tear (arrow). Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. 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 . An alternative way of fastening the allograft to the donor knee involves harvesting the meniscus with a small bone plug attached to each root and then securing the plugs within osseous tunnels drilled in the recipient tibia. Kim SJ, Choi CH. 3. 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. AJR Am J Roentgenol 211(3):519527, De Smet AA. The reported prevalence is 0.06% to 0.3%.25 the posterior horn is usually much larger than the anterior horn (the Vertical flap (oblique, flap, parrots beak) tears are unstable tears and occur in younger patients. 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. Radiographs are usually not diagnostic, but they may show a MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. 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 . Another finding is the abnormal size or shape of the meniscus, which would indicate damaged surfaces [, To provide a greater degree of accuracy, De Smet advocated the two-slice-touch rule. To call a definite tear, one should see increased signal contacting the articular surface of the menisci on at least two images (sagittal or coronal). The post arthrogram view (13B) reveals gadolinium within the repair site. Arthroscopy evaluation found a lateral meniscus peripheral (red-white zone) longitudinal tear. high fibula head and a widened lateral joint space.20 Several 2014; 43:10571064, McCauley TR. ; Lee, S.H. 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 congenitally absent meniscus appears to influence the development an adult), and approximately twice the size of the anterior horn on Posteroinferior displacement of the meniscal tissue (arrowheads) is also diagnostic of recurrent tear. It is located in the lateral portion of the knee interior of the knee joint. Arthrofibrosis and synovitis are also relatively common. Discoid medial menisci are much less common than discoid lateral menisci,24 and they may be bilateral. Sagittal T2-weighted (8B) and fat-suppressed coronal T2-weighted (8C) images reveal fluid signal (arrows) extending into the meniscal substance indicating a recurrent tear which was confirmed at second look arthroscopy. The anomalous insertion Sagittal proton density-weighted image (8A) through the medial meniscus demonstrates signal extending to the tibial surface (arrow). The lateral meniscus is produced by the varus tension and tibial IR. Tears Disadvantages include increased cost, increased patient time, potential for adverse reactions to contrast agent compared to conventional MRI and lack of joint distention. Following partial meniscectomy, the knee is at increased risk for osteoarthritis. Shepard et al have done a nice job of telling us just how frequently this mistake can be made by fellowship trained musculoskeletal radiologists. Kijowski et al. 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. Repair techniques include side-to-side repair, stabilization with suture anchors, and the transtibial pull-out technique (figure 4).12. Kim EY, Choi SH, Ahn JH, Kwon JW. Surgical Outcomes Lysholm Score 2059-2066, Kinsella S.D., and Carey J.L. described in thrombocytopenia absent radius syndrome (TAR syndrome).2,3 Bilateral hypoplasia of the medial meniscus has also been reported.4. Kelly BT, Green DW. A recurrent tear was proved at second look arthroscopy. of the meniscus. to the base of the ACL or the intercondylar notch. The meniscus can separate from the joint capsule or tear through the allograft. Anterior horn of the lateral meniscus: another potential pitfall in MR imaging of the knee. This has also been described as grade 2 signal [, Sagittal fat-suppressed T2 image of a 14-year-old patient showing a grade 2 signal in the posterior horn of the medial meniscus (PHMM). The medial meniscus is more tightly anchored than the lateral meniscus, allowing for approximately 5mm of anterior-posterior translation. 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. 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. At the time the article was last revised Yahya Baba had High signal close to fluid intensity contacts the tibial surface on the sagittal T2-weighted image (11B) and is equivocal. 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. tear. 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. Discoid medial meniscus. Proper preoperative sizing of the allograft is critical for surgical success and usually performed with radiographs. These are like large radial tears and can destabilize a large portion of the meniscus. Because there is less pressure on the meniscus there, it is difficult to evaluate the anterior region of the meniscus. Dickhaut SC, DeLee JC. No meniscal tear is seen, but the root attachment was also noted to be Samoto N, Kozuma M, Tokuhisa T, Kobayashi K. Diagnosis of discoid lateral meniscus of the knee on MR imaging. Radiology. The medial meniscus covers 60% of the medial compartment. Sagittal proton density-weighted image (9A) demonstrates no high signal abnormality. The posterior cruciate ligament is intact. At least one meniscofemoral ligament is present in 7093 % Of knees Kaplan EB. published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). 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. A Considered a feature of knee osteoarthritis. menisci (Figure 8). does not normally occur.13. Indications for meniscal repair typically include posttraumatic peripheral (red zone) longitudinal tears located near the joint capsule, ideally in younger patients (less than 40). 1 ). 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. The posterior root lies anterior to the posterior cruciate ligament. The most important clinical concern at the time of MRI imaging is often high-grade articular cartilage loss. Of the 14 athletes, 8 repairs were performed, 5 patients . At the time the case was submitted for publication Mostafa El-Feky had no recorded disclosures. According to one source, they are thought to account for ~10% of all arthroscopic meniscectomies 5. attachment of the posterior horn is the Wrisberg meniscofemoral morphology but lacks its posterior attachments; ie, the meniscotibial Lateral meniscus extrusion was present in six (23%) of 26 LMRTs and five (2.2%) of 231 patients with normal meniscus roots ( P < .001). the intercondylar notch, most commonly to the mid ACL, and less commonly Horizontal (degenerative) tears run relatively parallel the tibial plateau. For DSR inquiries or complaints, please reach out to Wes Vaux, Data Privacy Officer, Both ligaments attach distally to the posterior horn of the lateral meniscus and contribute to posterior drawer stability . Kocher MS, Klingele K, Rassman SO. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. 2012;199(3):481-99. When bilateral, they are usually symmetric. meniscus are not uncommon; they include an anomalous insertion of the Close clinical correlation is advised before recommending surgery based on this finding alone. 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. 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). No paralabral cyst. Exam showed a mild effusion and medial joint line tenderness. 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. 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. AJR Am J Roentgenol. 300). menisci develop from this mesenchymal tissue in a site where this tissue incomplete breakdown of the central meniscus, but this is now disputed, 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. These tears are usually degenerative in nature and usually not associated with a discrete injury [. 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. On imaging alone, the radiologist may not be able to distinguish a residual tear (failed repair) from a recurrent tear in the same location. During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. 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. MR imaging is useful for evaluation of many possible complications following meniscal surgery. The examiner can test the entire posterior horn up to the middle segment of the meniscus using the IR of the tibia followed by an extension. joint: Morphologic changes and their potential role in childhood mesenchymal mass that differentiates into the tibia, femur, and Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. 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. Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), Posterior Instability and Labral Pathology, Imaging Evaluation of the Painful or Failed Shoulder Arthroplasty, Other Entities: PLRI, HO, Triceps, and Plica, MRI-Arthroscopy Correlations in the Overhead Athlete, Acetabular Fossa, Femoral Fovea, and the Ligamentum Teres. Total meniscectomy is rarely performed unless the meniscus is so severely damaged that no salvageable meniscal tissue remains. MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. ligament will help to exclude these conditions.5 In the first There is no universally accepted system for classifying meniscal tear patterns. The ends of the anterior and posterior horns are firmly attached to the tibia at their roots. Torn lateral meniscus with superomedial and posterior flipped anterior horn. When it involves the posterior root, medial root tears are easier to diagnose than lateral root tears. 2006; 88:660667, Boutin RD, Fritz RC, Marder RA. 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. Repair devices including arrows, darts and sutures are used to approximate the torn edges of the meniscus. Concise, to-the-point text covers MRI for the entire musculoskeletal system, presented in a highly templated format. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. A meta-analysis of 44 trials. meniscal diameter. The example above demonstrates the importance of baseline MRI comparison when evaluating the postoperative meniscus. They may not even be apparent with an arthroscopic examination. Congenital discoid cartilage. If missing on MR images, a posterior root tear is present. Lateral meniscal variant with absence of the posterior coronary ligament. In contrast to the medial meniscus, the posterior horn of the lateral meniscus is additionally secured by the meniscofemoral ligaments (MFL). 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. Both horns of the medial meniscus are triangular with sharp points. In these cases, MR arthrography may provide additional diagnostic utility. In this section, the major patterns of tears are described and depicted in MRIs and arthroscopy images. joint, and they also protect the hyaline cartilage. 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. Most lateral meniscal tears are due to twisting or turning activities or falls. Of the 54 participants, 5 had PHLM tears and 49 were normal. 2012;20(10):2098-103. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. 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. Analytical, Diagnostic and Therapeutic Techniques and Equipment 13. To assess the prevalence of meniscal extrusion and its . 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. during movement, and less commonly joint-line tenderness, reduced 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 Additionally, the postoperative complication of new extensive synovitis is apparent on the axial view (18D). The fat-suppressed sagittal T1-weighted post arthrogram view (7C) demonstrates gadolinium extending into the meniscal substance. Discoid lateral meniscus was originally believed to result from an The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. You can use Radiopaedia cases in a variety of ways to help you learn and teach. | 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. Get unlimited access to our full publication and article library. of the transverse ligament is comparable to the general population.5. variants of the meniscus are relatively uncommon and are frequently > 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% Media community. collapse and widening of the medial joint space (Figure 7). 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. in this case were attributed to an anterior cruciate ligament tear The patient underwent meniscal repair but had recurrent pain prompting repeat MRI 8 months post-operative. There are The main functions 6. include hypoplastic menisci, absent menisci, anomalous insertion of the The MRI revealed a vertical flap (oblique) tear of the medial meniscus. Intact meniscal roots. slab-like configuration on sagittal MR images, with > 3 bowties 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 [.

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