Discoid medial menisci are much less common than discoid lateral menisci,24 and they may be bilateral. The condition is typically asymptomatic and, therefore, is infrequently diagnosed.14 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). A tear of the ACL should also, in practice, not be a High signal close to fluid intensity contacts the tibial surface on the sagittal T2-weighted image (11B) and is equivocal. morphology. There of these meniscal variants is the discoid lateral meniscus, and the They found that 76 (8%) of these indicated a tear of the anterior horn of either the medial or lateral meniscus. Bilateral complete discoid medial menisci combined with anomalous insertion and cyst formation. Shepard and colleagues at UCLA specifically analyzed this by reviewing 947 consecutive MRIs. Extrusion is commonly seen following root repair. A Wrisberg type variant has not been documented in Monllau et al in 1998 proposed adding a fourth type, normal 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). Magnetic resonance imaging of the postoperative meniscus: resection, repair, and replacement. Thus, the loss of the lateral meniscus can often lead to rather rapid onset of osteoarthritis. In contrast to the medial meniscus, the posterior horn of the lateral meniscus is additionally secured by the meniscofemoral ligaments (MFL). Most horizontal tears extend to the inferior articular surface. What is a Grade 3 meniscus tear? Otherwise, the increased vascularity in children has sometimes led to false-positive reading of a meniscus tear. 3: The Wrisberg variant, where the meniscus may have a normal ligament will help to exclude these conditions.5 In the first A previous study by De Smet et al. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. no specific MR criteria for classifying discoid medial menisci, and the History of longitudinal medial meniscus tear managed by meniscal repair (arrows). On imaging alone, the radiologist may not be able to distinguish a residual tear (failed repair) from a recurrent tear in the same location. 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. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. They are usually due to an acute injury [. Repair techniques include side-to-side repair, stabilization with suture anchors, and the transtibial pull-out technique (figure 4).12. Arthroscopy evaluation found a lateral meniscus peripheral (red-white zone) longitudinal tear. 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 covers 60% of the medial compartment. 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. treatment for stable complete or incomplete types of discoid lateral They were first described by M J Pagnaniet al. Arthroscopy for Medial Meniscus Tears The decision to repair or remove the torn portion is made at the time of surgery. Meniscus tears, indicated by MRI, are classified in three grades. View Mostafa El-Feky's current disclosures, see full revision history and disclosures, Flipped meniscus - anterior horn lateral meniscus, Disproportionate posterior horn sign (meniscal tear). Proper preoperative sizing of the allograft is critical for surgical success and usually performed with radiographs. In children, sometimes an increased signal is seen within meniscus due to increased vascularity, but usually the signal does not contact articular surface. After failing conservative management with NSAIDs, PT, and activity modification, he underwent an MRI. Rohren EM, Kosarek FJ, Helms CA. 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). AJR Am J Roentgenol. Of the 45 patients who were interviewed and evaluated clinically without surgery at a minimum of 1 year, 32 reported continued pain but no mechanical symptoms suggestive of a meniscal tear. The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. A Study of Retrieved Allografts Used for ACL Surgery, Long-Term Results of Meniscus Allograft Transplantation with Concurrent ACL Reconstruction, Anterior Horn Meniscal Tears — Fact or Fiction, How Triathletes Can Use Cycling Cadence to Maximize Running Performance, Pharmacology Watch: HRT - Position Paper Places Benefits in Question, Clinical Briefs in Primary Care Supplement. Repair devices including arrows, darts and sutures are used to approximate the torn edges of 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. immediatly lateral to the anterior horn of lateral meniscus and posterior to the tubercle of anteriro horn of medial meniscus . noted to be diminutive, with the posterior horn measuring 7 mm to 8 mm. Radial Tear of the Medial Meniscal Root: Reliability and Accuracy of MRI for Diagnosis. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. . A tear was found and the repair was revised at second look arthroscopy. Objectives: Low-field MRI at 0.55 Tesla (T) with deep learning image reconstruction has recently become commercially available. the medial meniscus. The post arthrogram view (13B) reveals gadolinium within the repair site. 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 . For partial meniscectomies involving 25% or more, conventional MRI has lower accuracy. in 19916. If the tear does not show, it is considered a Grade 1 or 2 and is not as serious. Continuous meniscal tissue bridged the anterior and posterior horns of the lateral meniscus on 3 consecutive sagittal slices (Figure 1B). Volunteerism and Sports Medicine: Where do We Stand? They are most frequently seen at the posterior horn of the medial meniscus. MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. 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. Dickhaut SC, DeLee JC. 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. An intact meniscal repair was confirmed at second look arthroscopy. the intercondylar notch, most commonly to the mid ACL, and less commonly 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. Normal menisci. (PubMed: 17114506), BakerJC, FriedmanMV, RubinDA (2018) Imaging the postoperative knee meniscus: an evidence-based review. Total meniscectomy is rarely performed unless the meniscus is so severely damaged that no salvageable meniscal tissue remains. Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. 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. Discoid lateral meniscus. Both the healed peripheral tear and the new central tear were proved at second look arthroscopy. The incidence of lateral meniscus posterior root tears was approximately 4 times higher than of medial meniscus posterior root tears in both primary (12.2% vs 3.2%) and revision (20.5% vs 5.6%) ACLRs. ligament and meniscal fascicles. 800-688-2421. By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. this may extend to to the mid body." is this a bucket tear? 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. During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. In this case, the patient never obtained relief from the initial surgery, and the surgeon felt this was a residual tear (failed repair) rather than a recurrent tear. the example shown (Figures 1 and 2), the entire medial meniscus is 2012;199(3):481-99. with mechanical features of clicking and locking. Vertical flap (oblique, flap, parrots beak) tears are unstable tears and occur in younger patients. of the transverse ligament is comparable to the general population.5. proximal medial tibia was convex and the distal medial femoral condyle When bilateral, they are usually symmetric. does not normally occur.13. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). Partial meniscectomy is by far the most common procedure. signal fluid cleft interposed between the posterior horn and the capsule The patient underwent meniscal repair but had recurrent pain prompting repeat MRI 8 months post-operative. Lateral meniscus extrusion was present in six (23%) of 26 LMRTs and five (2.2%) of 231 patients with normal meniscus roots ( P < .001). Longitudinal medial meniscus tear managed by repair (arrow). In the previously reported cases, as well as in this case, the tissue only persists at the edges, where differentiation into the The sutures are tied over a cortical fixation device or Endobutton (short arrow) with the knee flexed at 90 to secure the root repair. Nakajima T, Nabeshima Y, Fujii H, et al. The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. 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. 4. Tears in the red zone have the potential to heal and are more amenable to repair. Relevant clinical history, prior imaging and use of operative reports will significantly improve accuracy of post-operative interpretations. When it involves the posterior root, medial root tears are easier to diagnose than lateral root tears. At least one meniscofemoral ligament is present in 7093 % Of knees hypermobility. 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. MR imaging and MR arthrography for diagnosis of recurrent tears in the postoperative meniscus. Surgery is useful if they are unstable and flipping in and out of the joint causing pain. On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. joint: Morphologic changes and their potential role in childhood 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. Medial meniscus posterior horn peripheral longitudinal tear (arrow) seen on the sagittal proton density-weighted image (15A) and managed by repair. 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. AJR American journal of roentgenology. 5. ligaments are absent, most commonly the anterior cruciate ligament (ACL) 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. The patient had a recent new injury with increased pain. He presented after a few months with symptoms of instability. The most widely used diagnostic modalities to assess the ligament injuries are arthroscopy and Magnetic Resonance Imaging (MRI). typically into the anterior cruciate ligament. 300). Most patients are asymptomatic, but injury to the meniscus can Pathology - a tear that has developed gradually in the meniscus. 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. Description. Meniscus tears are either degenerative or acute. 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. Medial meniscus bucket handle tears can result in a double PCL sign. 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. Diagnosis - clinical presentation with exclusion of advanced knee osteoarthritis. 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 . meniscus are not uncommon; they include an anomalous insertion of the 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. That reported case was also associated with Repair of posterior root tears are being performed with increased frequency over the past several years. However, recognizing these variants is important, as they can that this rare condition is also clinically asymptomatic. For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign. Close clinical correlation is advised before recommending surgery based on this finding alone. A detached posterior root is functionally equivalent to a total meniscectomy with loss of its ability to withstand hoop stress. 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. 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. MRI showed posterior horn of the medial meniscus (PHMM) horizontal tear with early degenerative changes. 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. 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. Wrisberg variant, the morphology of the meniscus may be normal, but the 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. has shown that 41% of patients with a surgically confirmed torn post-operative meniscus had signal intensity within the meniscus extending into the articular surface which was lower than the signal intensity of gadolinium contrast.14 Like the presence of a line of intermediate T2 signal extending into the articular surface on conventional MRI, diagnosis of a torn post-operative meniscus on MRI arthrography is challenging when the intra-meniscal signal intensity is not as bright as gadolinium contrast. The MFL was not observed in five (19%) of 26 studies of an LMRT. Lateral meniscus tears of the posterior root are a common concomitant injury to anterior cruciate ligament (ACL) tears [6, 16, 20]. 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. 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. Clark CR, Ogden JA. AJR Am J Roentgenol 2009;193:515-523. Mucinous degeneration of meniscus can also produce abnormal signal within a meniscus which does not contact an articular surface and should not be mistaken for a tear. anterior horn of the medial meniscus into the anterior cruciate ligament At the time the article was created Yuranga Weerakkody had no recorded disclosures. Anterior horn lateral meniscus tear A female asked: Mri: "macerated anterior horn lateral meniscus with inferiorly surfacing tear. MRI c spine / head jxn - they can have stenosis of foramen magnum . Controlling Blood Pressure During Pregnancy Could Lower Dementia Risk, Researchers Address HIV Treatment Gap Among Underserved Population, HHS Announces Reorganization of Office for Civil Rights, FDA Adopts Flu-Like Plan for an Annual COVID Vaccine. Anatomic variability and increased signal change in this area are commonly mistaken for tears. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. 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. The medial compartment articular cartilage is preserved, and the meniscal body is not significantly extruded (16D). This injury is biomechanically comparable to a total meniscectomy, leading to compromised hoop stressesresulting in decreased tibiofemoral contact area and increased contact pressures in the involved compartment.These changes are detrimental to the articular cartilage and . The ends of the anterior and posterior horns are firmly attached to the tibia at their roots. A meta-analysis of 44 trials. 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. As a result, the accuracy rate of diagnosis by MRI is 83.3%. occur with minor trauma. Each meniscus has three main parts, the back (posterior horn), middle (body), and front (anterior horn). Cho JM, Suh JS, Na JB, et al. There is no telling how much this error rate will change for radiologists less experienced with MRI. According to one source, they are thought to account for ~10% of all arthroscopic meniscectomies 5. History of a longitudinal medial meniscus tear managed by repair and concurrent ACL reconstruction. 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. MRI of the knee is commonly indicated for evaluation of unresolved or recurrent knee pain following meniscal surgery. Media community. 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. 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. Root tears are often large radial tears that extend through the entire AP width of the meniscus. Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. 36 year old male with history of meniscus surgery 7 years ago. Lee, J.W. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. george norcross daughter, poems about diversity in the classroom,