The torn edges are aligned, and stable fixation applied with sutures or bioabsorbable implants at approximately 5 mm intervals. 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. Anterior lateral cysts extended . An intact meniscal repair was confirmed at second look arthroscopy. (as previously described), meniscal cyst,26 discoid lateral meniscus in the same knee (Figure 9),25 and pathologic medial patella plica.27. Collagen fibers are arranged for transferring compressive loads into circumferential hoop stresses, secured by radially oriented tie fibers. be misinterpreted for more significant pathology on MRI. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. Weight-bearing knee X-rays showed a 50 % narrowing in the medial compartment. occur with minor trauma. MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. The remaining 42 cases were located in the red zone (19 cases) or the red-white zone. Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images. On MR arthrography, (12B), gadolinium extends through the repair site indicating a tear. 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). Radial or oblique tear congurations close to or within the meniscus . both enjoyable and insightful. the posterior horn is usually much larger than the anterior horn (the The discoid lateral-meniscus syndrome. anterior horn of the medial meniscus into the anterior cruciate ligament 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. Most studies have shown increased accuracy for direct and indirect MR arthrography compared to conventional MRI for partial meniscectomies of 25% or more.16. CT arthrography is recommended for patients with MRI contraindications or when extensive susceptibility artifact from hardware obscures the meniscus. Direct intraarticular injection of 20-50 mL of dilute iodinated contrast is performed with rapid image acquisition using multidetector CT with high spatial resolution and multiplanar reformatted images. 2006;239(3):805-10. They often tend to be radial tears extending into the meniscal root. No paralabral cyst. The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. 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. With age, increased connective tissue stiffness of the meniscus develops secondary to elastin degradation and collagen rigidification.2. A previous study by De Smet et al. Congenital discoid cartilage. also found various MRI characteristics highly specific for detection of a recurrent tear including a line of intermediate-to-high signal or high signal through the meniscus extending into the articular surface on T2-weighted images with 95.8% specificity and change in the signal intensity pattern through the meniscus on intermediate weighted or T2-weighted images when compared to the baseline MRI with 98.2% specificity. 2014; 43:10571064, McCauley TR. A detached posterior root is functionally equivalent to a total meniscectomy with loss of its ability to withstand hoop stress. The insertion site The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). 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. immediatly lateral to the anterior horn of lateral meniscus and posterior to the tubercle of anteriro horn of medial meniscus . 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. A tear of the anterior horn of the lateral meniscus is damage to the front part of one of the two structures that act as shock absorbers between the thigh bone and the lower leg, explains The Steadman Clinic. Pre-operative fat supressed coronal proton density-weighted image (19A) demonstates a posterior root radial tear (arrow). 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. Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. in this case were attributed to an anterior cruciate ligament tear Most patients are asymptomatic, but injury to the meniscus can insertion of the medial meniscus (AIMM) has been described, and it is The Wrisberg variant may present with a Normal menisci. Sagittal proton density-weighted (14A) and coronal T1-weighted (14B) images reveal a recurrent bucket-handle tear through the original repair site with typical findings of a displaced meniscal flap (arrow) into the intercondylar notch. 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. Klingele KE, Kocher MS, Hresko MT, et al. Close clinical correlation is advised before recommending surgery based on this finding alone. On examination, there was marked medial joint line tenderness and a large effusion. Comparison of Postoperative Antibiotic Regimens for Complex Appendicitis: Is Two Days as Good as Five Days? The lateral meniscus is produced by the varus tension and tibial IR. About KOL ; Learn more about our technology and how more and more universities, research organizations, and companies in all industries are using our data to lower their costs. 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. (middle third), or Type 3 (superior third; intercondylar notch) (Figure Objectives: Low-field MRI at 0.55 Tesla (T) with deep learning image reconstruction has recently become commercially available. Because there is less pressure on the meniscus there, it is difficult to evaluate the anterior region of the meniscus. Kaplan EB. Cho JM, Suh JS, Na JB, 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. The sagittal proton density-weighted image (13A) demonstrates linear high signal extending to the femoral and tibial surfaces (arrow). To assess the prevalence of meniscal extrusion and its . varus deformity (Figure 3). Meniscal tears are common and often associated with knee pain. 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. and ACL tears can be mistaken for AIMM, but carefully tracing the of the AIMM into the ACL is classified as Type 1 (inferior third), Type 2 The clinical significance of anterior horn meniscal tears diagnosed on magnetic resonance images. The MRI also demonstrated moderate degenerative spurring at the lateral joint compartment, a large knee joint effusion with . medial meniscus, discoid lateral meniscus, including the Wrisberg 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. treatment for stable complete or incomplete types of discoid lateral History of longitudinal medial meniscus tear managed by meniscal repair (arrows). Another MRI was later performed due to worsening symptoms, and demonstrated a bucket-handle tear with complete anterior luxation of the posterior horn of the left lateral meniscus (Figs. Radiology. 7.2 Medial and Lateral Menisci Medial meniscus is larger than the lateral meniscus and is more "open" (=less C-like) and less wide. Meniscus tears are either degenerative or acute. MRI Findings: Medial meniscus: Tear of the posterior horn seen to the inferior articular surface continuing into the posterior body and becoming more vertical. AJR Am J Roentgenol 2009;193:515-523. It is often explained by fibers of the anterior cruciate ligament and the covering synovium . Medial meniscus bucket handle tears can result in a double PCL sign. They divide the meniscus into superior and inferior halves (Fig. Otherwise, the increased vascularity in children has sometimes led to false-positive reading of a meniscus tear. A meniscus is a crescent-shaped fibrocartilaginous structure that 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. Fat supressed coronal proton density-weighted (19C, D) and sagittal proton density-weighted (19E) images demonstrate postoperative changes from interval posterior horn partial meniscectomy with a thin rim of posterior horn remaining (arrow) and subchondral fractures in the medial femoral condyle and medial tibial plateau (arrowheads) with marked progression of full-thickness chondral loss in the medial compartment and extruded meniscal tissue. include hypoplastic menisci, absent menisci, anomalous insertion of the Of the 14 athletes, 8 repairs were performed, 5 patients . The diagnosis of tears of the anterior horn of the meniscus by magnetic resonance imaging (MRI) is sometimes different from that obtained by arthroscopic examination. 2013;106(1):91-115. tissue only persists at the edges, where differentiation into the There was no evidence of meniscal extrusion or a meniscal ghost sign (Fig. | 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. Grade II hyperintense horizontal signal of posterior horn of medial meniscus is noted. 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 . Kocher MS, Klingele K, Rassman SO. meniscus is partial meniscal excision, leaving a 6- to 7-mm peripheral 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. ligaments are absent, most commonly the anterior cruciate ligament (ACL) 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 2012;20(10):2098-103. 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. 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. Lateral meniscus posterior horn peripheral longitudinal tear managed by repair. Normal Sagittal T2-weighted image (10B) reveals no fluid at the repair site. Results: Arthroscopic examination of the anterior horn of the lateral meniscus in all 22 patients was normal. The posterior cruciate ligament is intact. At the time the article was created Yuranga Weerakkody had no recorded disclosures. 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. Magnetic resonance imaging of the postoperative meniscus: resection, repair, and replacement. In contrast to the medial meniscus, the posterior horn of the lateral meniscus is additionally secured by the meniscofemoral ligaments (MFL). The medial meniscus is more tightly anchored than the lateral meniscus, allowing for approximately 5mm of anterior-posterior translation. The patient underwent meniscal repair but had recurrent pain prompting repeat MRI 8 months post-operative. The ligament of Humphrey inserted on average 0.9 consecutive images lateral to the PCL without an PHLM tear and 4.7 with an PHLM tear; the ligament of Wrisberg inserted on average 3.0 consecutive images without an PHLM tear and 4.5 with an PHLM tear . 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. 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. Medial meniscus posterior horn peripheral longitudinal tear (arrow) seen on the sagittal proton density-weighted image (15A) and managed by repair. Repair techniques include side-to-side repair, stabilization with suture anchors, and the transtibial pull-out technique (figure 4).12. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. 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). The patient underwent a successful partial medial meniscectomy and was encouraged to seek low-impact exercise. 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. meniscal injury. RESULTS. Direct and indirect MR arthrography have been shown to be superior to conventional MRI for detection of recurrent meniscal tears in greater than 25% partial meniscectomies and meniscal repairs; however, conventional MRI is commonly used for initial evaluation of the postoperative meniscus with MR arthrography reserved for equivocal cases. 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. Fukuta S, Masaki K, Korai F. Prevalence of abnormal findings in magnetic resonance images of asymptomatic knees. The incidence was calculated based on arthroscopic findings, and the potential secondary signs of meniscal ramp tears were evaluated on MRI. Kim SJ, Moon SH, Shin SJ. This emphasizes the importance of baseline MRI comparison for evaluation of the postoperative meniscus.3. A 22-years old male presented with injury to right knee in a road traffic accident MRI images shows double posterior horn of lateral meniscus and absent anterior horn in coronal (A: PD; B: STIR; C . A tear of the lateral meniscus can occur from a sudden injury, or from chronic wear and overload. A The medial meniscus is asymmetrical with a larger posterior horn. Lateral meniscal variant with absence of the posterior coronary ligament. 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. Shepard et al have done a nice job of telling us just how frequently this mistake can be made by fellowship trained musculoskeletal radiologists. Sagittal proton density-weighted image (7A) through the medial meniscus demonstrates increased signal extending to the tibial surface (arrow). Tears can be characterized by length, depth, shape, gap, displacement, stability, dysplasia (discoid) 4. 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 patient subsequently underwent successful partial medial meniscectomy. 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. 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. The self-reported complication rate for partial meniscectomy is 2.8% and meniscus repair is 7.6%. patella or Hoffas fat pad, and should be fairly easily differentiated Type 1: A complete slab of meniscal tissue with complete tibial coverage. 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 ]. 4). This article focuses on > 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% Surgery is useful if they are unstable and flipping in and out of the joint causing pain. Tachibana Y, Yamazaki Y, Ninomiya S. Discoid medial meniscus. Skeletal radiology. 1427-143. 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 anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. MR criteria are used to make the diagnosis. from AIMM. They often tend to be radial tears extending into the meniscal root. Longitudinal lateral meniscus tear status post repair (arrow). They are most frequently seen at the posterior horn of the medial meniscus. ligament will help to exclude these conditions.5 In the first Case 9: posterior root of medial meniscus, View Yuranga Weerakkody's current disclosures, see full revision history and disclosures, anterior cruciate ligament avulsion fracture, posterior cruciate ligament avulsion fracture, Ahlback classification system in assessing osteoarthritis of the knee joint, Kellgren and Lawrence system for classification of osteoarthritis, anterior cruciate ligament mucoid degeneration, MRI grading system for meniscal signal intensity, shortening or absence of the root on sagittal images, vertical fluid cleft on coronal fluid-sensitive (T2) images. Discoid medial menisci are much less common than discoid lateral menisci,24 and they may be bilateral. On MR images of the knee it is sometimes impossible to determine with confidence if a focus of high signal in the meniscus is confined to the substance of the meniscus or if it extends to involve the surface. Most horizontal tears extend to the inferior articular surface. Grades 1 and 2 are not considered serious. Pathology - a tear that has developed gradually in the meniscus. 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. 36 year old male with history of meniscus surgery 7 years ago. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. However, clinically significant tears that can mechanically impinge were unlikely to have been missed. In these cases, MR arthrography may provide additional diagnostic utility. 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. AJR American journal of roentgenology. structure on sagittal images on T1, proton density, and fat-saturated We hope you found our articles Check for errors and try again. Financial Disclosure: None of the authors or planners for this educational activity have relevant financial relationships to disclose with ineligible companies whose primary business is producing, marketing, selling, reselling, or distributing healthcare products used by or on patients. Singh K, Helms CA, Jacobs MT, Higgins LD. meniscal diameter. 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. 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. 5. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. The medial meniscus covers 60% of the medial compartment. It has been calculated that the lateral meniscus absorbs about 70% of the forces across the lateral compartment of the knee. 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. Arthrofibrosis and synovitis are also relatively common. Tear between 1-4 cm vertical tear red-red meniscal root <40 yo Maybe concominant ACL surgery . If missing on MR images, a posterior root tear is present. The MRI showed complete ACL tear with displaced bucket handle medial meniscus tear. 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. 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 lateral meniscus tear A female asked: Mri: "macerated anterior horn lateral meniscus with inferiorly surfacing tear. 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. 3. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients. Media community. The most widely used diagnostic modalities to assess the ligament injuries are arthroscopy and Magnetic Resonance Imaging (MRI). 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 morphology. They found that 76 (8%) of these indicated a tear of the anterior horn of either the medial or lateral meniscus. discoid lateral meniscus is a relatively uncommon developmental variant Diagnosis - clinical presentation with exclusion of advanced knee osteoarthritis. Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. hypermobility. While this test will show a tear up to 90% of the time, it does not always. 2008;191(1):81-5. rim circumferentially, anteriorly, and posteriorly,19 which However, many clinicians opt to use conventional MRI as the initial postoperative imaging study and reserve MR arthrography for equivocal cases. On the proton density-weighted image (12A) persistent high signal extends to the tibial and femoral surfaces (arrow). small meniscus is also seen in the wrist joint. Evaluate the TCO of your PACS download >, 750 Old Hickory Blvd, Suite 1-260Brentwood, TN 37027, Focus on Musculoskeletal and Neurological MRI, Meniscal tears: the effect of meniscectomy and of repair on intraarticular contact areas and stress in the human knee. Surgical Outcomes Lysholm Score An intact meniscal repair was confirmed at second look arthroscopy. Kijowski et al. However, few studies have directly compared the medial and lateral root tears. Meniscal root tear. 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? 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.