The congenitally absent meniscus appears to influence the development 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. 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. 2014; 43:10571064, McCauley TR. They often tend to be radial tears extending into the meniscal root. of the meniscus. Grade II hyperintense horizontal signal of posterior horn of medial meniscus is noted. During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. To provide the highest quality clinical and technology services to customers and patients, in the spirit of continuous improvement and innovation. On examination, the patient had medial joint line tenderness with positive McMurray test. In cases like this, MR arthrography is quite helpful. 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. no financial relationships to ineligible companies to disclose. Kaplan EB. Anomalous On examination, there was marked medial joint line tenderness and a large effusion. (Figure 1). Pagnani M, Cooper D, Warren R. Extrusion of the Medial Meniscus. The ideal technique for imaging the postoperative meniscus is a matter of active controversy and depends on the operation performed, surgeon preference and clinical question (concern for recurrent meniscal tear versus articular cartilage). Bilateral discoid medial menisci: Case report. The meniscus can separate from the joint capsule or tear through the allograft. What causes abnormal mobility in the medial meniscus? The insertion site It is located in the lateral portion of the knee interior of the knee joint. Zonal variation is also seen in the density of meniscus cells and their phenotypes with a chondrocytic inner zone and fibroblastic outer zone. The reported prevalence is 0.06% to 0.3%.25 Am J Sports Med 2010; 38:15421548, LaPrade RF, Matheny LM, Moulton SG, James EW, Dean CS. They maintain a relatively constant distance from the periphery of the meniscus [. Radiology. Neuschwander DC, Drez D Jr, Finney TP. appearance.12 It is now believed that the knee develops from a rim circumferentially, anteriorly, and posteriorly,19 which 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. 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. Rao PS, Rao SK, Paul R. Clinical, radiologic, and arthroscopic assessment of discoid lateral meniscus. 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. 2012;199(3):481-99. Analytical, Diagnostic and Therapeutic Techniques and Equipment 13. When interpreting MR images of the knee, it is important to assess for any change from the expected shape of the menisci. Type 1: A complete slab of meniscal tissue with complete tibial coverage. However, recognizing these variants is important, as they can Repair techniques include side-to-side repair, stabilization with suture anchors, and the transtibial pull-out technique (figure 4).12. 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. What is a Grade 3 meniscus tear? The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. 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. MRI of the knee is commonly indicated for evaluation of unresolved or recurrent knee pain following meniscal surgery. The MRI revealed a vertical flap (oblique) tear of the medial meniscus. runs from the anterior horn of the medial meniscus to either the ACL or 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). Discoid lateral meniscus was originally believed to result from an Radial or oblique tear congurations close to or within the meniscus . They are usually due to an acute injury [. By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. Sagittal PD (. The sensitivity of mri in detecting meniscal tears is generally good, ranging from 70-98%, with specificity in the same range in many studies. 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. Sagittal T2-weighted image (10B) reveals no fluid at the repair site. Sagittal proton density-weighted image (8A) through the medial meniscus demonstrates signal extending to the tibial surface (arrow). Menisci ensure normal function of the 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. diminutive (1 mm) with no increased signal to suggest root attachment Pre-operative fat supressed coronal proton density-weighted image (19A) demonstates a posterior root radial tear (arrow). 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. Davidson D, Letts M, Glasgow R. Discoid meniscus in children: Treatment and outcome. Following a meniscal repair procedure, the meniscus can be categorized as healed if there is no fluid signal in the repair, partially healed if fluid signal extends into less than 50% of the repair site, or not healed if fluid signal extends into greater than 50% of the repair site. meniscus are not uncommon; they include an anomalous insertion of the Check for errors and try again. be misinterpreted for more significant pathology on MRI. Extension to the anterior cortex of . However, the tear changes plane of orientation over its course. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. The lateral meniscus is produced by the varus tension and tibial IR. insertion of the medial meniscus (AIMM) has been described, and it is 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 . Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. ligament, and the posterior horn may translate or rotate due to For partial meniscectomies involving 25% or more, conventional MRI has lower accuracy. Kim SJ, Choi CH. Renew or update your current subscription to Applied Radiology. Kijowski et al. 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. The anomalous insertion The avulsed anterior horn of the lateral meniscus is flipped over and situated above the posterior horn. 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. Congenital absence of the meniscus is extremely rare and has been documented in TAR syndrome and in isolated case reports.2,3 of the transverse ligament is comparable to the general population.5. If missing on MR images, a posterior root tear is present. 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. in 19916. Discoid lateral meniscus and the frequency of meniscal tears. ; Lee, S.H. 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. Suprapatellar plica noticed, with no related cartilaginous erosions. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. Discoid meniscus in children: Magnetic resonance imaging characteristics. Kijowski et al. 1). medial meniscus, and not be confined to the ACL as seen in an ACL tear. Normal menisci. Anterior horn of the lateral meniscus: another potential pitfall in MR imaging of the knee. Lateral meniscus tears of the posterior root are a common concomitant injury to anterior cruciate ligament (ACL) tears [6, 16, 20]. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. Schwenke M, Singh M, Chow B Anterior Cruciate Ligament and Meniscal Tears: A Multi-modality Review. This mesenchymal For information on new subscriptions, product Grade 3 is a true meniscus tear and an arthroscope is close to 100 percent accurate in diagnosing this tear. 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 300). Variations in meniscofemoral ligaments at anatomical study and MR imaging. Normal course and intensity of both cruciate ligaments. Sagittal proton density-weighted image (5B) through the medial meniscus at age 17 reveals an incomplete tibial surface longitudinal tear (arrow) in a new location and orientation. MRI plays a critical role in influencing the treatment decision and enables information that would obviate unnecessary surgery including diagnostic arthroscopy. Close clinical correlation is advised before recommending surgery based on this finding alone. . If the tear does not show, it is considered a Grade 1 or 2 and is not as serious. Fat suppressed sagittal T1-weighted MR arthrogram (5C) demonstrates gadolinium within the tear (arrow). Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. 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 . 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. Generally, Grades 1 and 2 are not considered serious. (1A) Proton density-weighted, (1B) T2-weighted, and (1C) fat-suppressed T1-weighted MR arthrographic sagittal images are provided. ADVERTISEMENT: Supporters see fewer/no ads. No gadolinium extension into the meniscus on fat-suppressed sagittal T1-weighted (9B) post arthrogram view. Tear between 1-4 cm vertical tear red-red meniscal root <40 yo Maybe concominant ACL surgery . menisci occurs. A meta-analysis of 44 trials. 3: The Wrisberg variant, where the meniscus may have a normal That reported case was also associated with In this section, the major patterns of tears are described and depicted in MRIs and arthroscopy images. Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. | 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. to the base of the ACL or the intercondylar notch. After failing conservative management with NSAIDs, PT, and activity modification, he underwent an MRI. The post arthrogram view (13B) reveals gadolinium within the repair site. This is because most tears occur in the posterior horns [, Whether a torn meniscus is reparable depends on the type or pattern of tear, its location, and the quality of the meniscal tissue. Both horns of the medial meniscus are triangular with sharp points. (as previously described), meniscal cyst,26 discoid lateral meniscus in the same knee (Figure 9),25 and pathologic medial patella plica.27. Most patients are asymptomatic, but injury to the meniscus can A previous study by De Smet et al. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. FSE T2-weighted images, with a slab-like appearance on coronal images. . Case study, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-75066. The posterior horn is always larger than the anterior horn. De Smet A. attachment of the posterior horn is the Wrisberg meniscofemoral mesenchymal mass that differentiates into the tibia, femur, and 9 The lateral meniscus is more loosely attached than the medial and can translate approximately 11mm with normal knee motion. At the time the article was last revised Yahya Baba had Mild irregularities of the meniscal contour may be present, particularly in the first 6-9 months after surgery which tend to smooth out and remodel over time.15 For partial meniscectomies involving less than 25% of the meniscus, conventional MRI is used with the same imaging criteria for evaluating a tear as the native meniscus linear intrasubstance increased signal extending to the articular surface, visualized on 2 images, either consecutively in the same orientation or in the same region in 2 different planes or displaced meniscal fragment (based on the assumption that imaging is spaced at 3 mm intervals). 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. 4). Kelly BT, Green DW. Discoid lateral meniscus of the knee joint: Nature, mechanism, and operative treatment. 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. While they can arise from a number of mechanisms, root tears are generally thought to be chronic 5. What is your diagnosis? It is usually seen near the lateral meniscus central attachment site. discoid lateral meniscus, including a propensity for tears to occur and As a result, the accuracy rate of diagnosis by MRI is 83.3%. Shepard and colleagues at UCLA specifically analyzed this by reviewing 947 consecutive MRIs. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. Knee Surg Sports Traumatol Arthrosc 2011; 19:147157, Gwathmey F.W., Golish S.R., Diduch D.R., et al: Complications in brief: meniscus repair. It is believed that discoid Examination showed lateral joint line tenderness and a positive McMurray sign. 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. Illustration of the medial and lateral menisci. Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG. 6 months post-operative she had increased pain prompting follow-up MRI. Mechanical rasping or trephination of the torn meniscus ends and parameniscal synovium is used to promote bleeding and vascular healing. 2020;49(1):42-49. 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. 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. These features constitute O'Donoghue unhappy triad. Meniscal root tears are defined as radial tears located within 1 cm from the meniscal attachment or a bony rootavulsion. 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. is in fact reducing the volume of the meniscus and restoring a normal Surgery is useful if they are unstable and flipping in and out of the joint causing pain. 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. This is a critical differentiation because the latter represents meniscal tears that can be least common is complete congenital absence of the menisci. Radiographs may A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. 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. 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. of these meniscal variants is the discoid lateral meniscus, and the diagnostic dilemma, as the AIMM band will be seen to extend to the Findings indicate an intact meniscus following partial meniscectomy with normal intrameniscal signal. He presented after a few months with symptoms of instability. Results: Arthroscopic examination of the anterior horn of the lateral meniscus in all 22 patients was normal. ligament and meniscal fascicles. AJR American journal of roentgenology. The medial meniscus covers 60% of the medial compartment. the posterior horn is usually much larger than the anterior horn (the