The avulsed anterior horn of the lateral meniscus is flipped over and situated above the posterior horn. The Journal of bone and joint surgery American volume. MR imaging evaluation of the postoperative knee. 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. Arthrofibrosis and synovitis are also relatively common. A detached posterior root is functionally equivalent to a total meniscectomy with loss of its ability to withstand hoop stress. Longitudinal lateral meniscus tear status post repair (arrow). 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. History of longitudinal medial meniscus tear managed by meniscal repair (arrows). Rohren EM, Kosarek FJ, Helms CA. 7 Therefore, it is important for the radiologist to be familiar with the appearance of a recurrent tear versus an untorn postoperative meniscus. 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. A meta-analysis of 44 trials. There is no universally accepted system for classifying meniscal tear patterns. ligaments and menisci causing severe knee dysplasia in TAR syndrome. The most frequent symptom is pain that usually begins with a minor (Tr. 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. It can be divided into five segments: anterior horn, anterior, middle and posterior segments, and posterior horn. 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. slab-like configuration on sagittal MR images, with > 3 bowties 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). ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. St. Louis County's newspaper of politics and culture Rao PS, Rao SK, Paul R. Clinical, radiologic, and arthroscopic assessment of discoid lateral meniscus. Pre-operative fat supressed coronal proton density-weighted image (19A) demonstates a posterior root radial tear (arrow). 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. Concise, to-the-point text covers MRI for the entire musculoskeletal system, presented in a highly templated format. noted to be diminutive, with the posterior horn measuring 7 mm to 8 mm. Am J Sports Med. Discoid lateral meniscus of the knee joint: Nature, mechanism, and operative treatment. {"url":"/signup-modal-props.json?lang=us"}, Weerakkody Y, Baba Y, Knipe H, et al. meniscus. . What causes abnormal mobility in the medial meniscus? Radial tears comprise approximately 15 % of tears in some surgical series [. 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. The most common sagittal magnetic resonance (MR) images. Among these 26 studies of an LMRT . 1991;7(3):297-300. 36 year old male with history of meniscus surgery 7 years ago. 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 . The medial meniscus is asymmetrical with a larger posterior horn. Heron, D, Bonnard C, Moraine C,Toutain A. Agenesis of cruciate Type 1: A complete slab of meniscal tissue with complete tibial coverage. The purpose of our study was to determine if cysts of the ACL are the origin of cysts adjacent to the AHLM. By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. Lateral meniscus tears of the posterior root are a common concomitant injury to anterior cruciate ligament (ACL) tears [6, 16, 20]. For partial meniscectomies involving 25% or more, conventional MRI has lower accuracy. The common insertion of the anterior cruciate ligament (ACL) and the AHLM root may provide a pathway for disease. Fukuta S, Masaki K, Korai F. Prevalence of abnormal findings in magnetic resonance images of asymptomatic knees. The meniscus may also become hypertrophic. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. signal fluid cleft interposed between the posterior horn and the capsule Magnetic resonance imaging (MRI) revealed an elongated free edge of the diffusely enlarged lateral meniscus extending toward the intercondylar region on coronal T1-weighted images (Figure 1A). 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. For information on new subscriptions, product The MRI revealed a longitudinal tear in the posterior horn of the lateral meniscus. 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 ]. Long-term outcome after arthroscopic meniscal repair versus arthroscopic partial meniscectomy for traumatic meniscal tears. snapping knee due to hypermobility. Findings indicate an intact meniscus following partial meniscectomy with normal intrameniscal signal. posterior horn of the medial meniscus include a triangular hypointense The MRI revealed a vertical flap (oblique) tear of the medial meniscus. Intact meniscal roots. 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. With age, increased connective tissue stiffness of the meniscus develops secondary to elastin degradation and collagen rigidification.2. 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. Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). discoid meniscus, although discoid medial menisci can occur much less patella or Hoffas fat pad, and should be fairly easily differentiated 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). There are (1A) Proton density-weighted, (1B) T2-weighted, and (1C) fat-suppressed T1-weighted MR arthrographic sagittal images are provided. MRI appearance of Wrisberg variant of discoid lateral meniscus. The MRI also demonstrated moderate degenerative spurring at the lateral joint compartment, a large knee joint effusion with . Repair techniques include side-to-side repair, stabilization with suture anchors, and the transtibial pull-out technique (figure 4).12. As visualized on sagittal MR images, the anterior horn of the medial meniscus is shorter than the posterior horn, whereas the anterior and posterior horns of the lateral meniscus are of equal length. 10 hypoplastic meniscus was not the cause of the patients pain, suggesting menisci occurs. partly divides a joint cavity, unlike articular discs, which completely It splits into two bands at the PCL, named Humphry(anterior to the PCL) and Wrisberg (posterior to the PCL). Pain is typically medial and activity-related (e.g. to tear. They often tend to be radial tears extending into the meniscal root. Anomalous Renew or update your current subscription to Applied Radiology. The main functions Problems encountered in a discoid medial meniscus are the same as a The sensitivity of mri in detecting meniscal tears is generally good, ranging from 70-98%, with specificity in the same range in many studies. (middle third), or Type 3 (superior third; intercondylar notch) (Figure posterior fascicles and meniscotibial ligament are absent and a high Of the 14 athletes, 8 repairs were performed, 5 patients . Sometimes T2 signal in a healed tear may look similar to fluid. It affects 4% to 5% of the patient population,6-9 with a much higher incidence, up to 13%, in the Asian patient population.10 It is the most common meniscal variant in children.11 Volunteerism and Sports Medicine: Where do We Stand? Kaplan EB. MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. 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. Both the healed peripheral tear and the new central tear were proved at second look arthroscopy. There was no history of a specific knee injury. 5 In the first instance, tears of the lateral aspect of the anterior horn of the medial meniscus are extremely uncommon and should not be a diagnostic Disadvantages include patient discomfort, increased cost, physician time needed for the procedure and radiation exposure during fluoroscopy. the intercondylar notch, most commonly to the mid ACL, and less commonly The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. 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. 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. of a case of discoid medial cartilage, with an embryological note. Medial meniscus posterior horn peripheral longitudinal tear treated with repair. medial meniscus, and not be confined to the ACL as seen in an ACL tear. 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. Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images. 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. 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 . Conventional MRI is useful for evaluation of posterior root morphology at the tibial tunnel fixation site, meniscal extrusion and articular cartilage. There is a medial and a lateral meniscus. horns to the meniscal diameter on a sagittal slice that shows a maximum History of medial meniscus posterior horn partial meniscectomy. 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. 3: The Wrisberg variant, where the meniscus may have a normal The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign. The anterior and posterior sutures are shuttled down the tibial tunnel (arrowhead). There are 3 main types, according to the Watanabe classification:18. Collagen fibers are arranged for transferring compressive loads into circumferential hoop stresses, secured by radially oriented tie fibers. Arthroscopy is considered gold standard in the diagnosis of knee ligament injuries, with diagnostic accuracy up to 94% [1], [2]; and can be used therapeutically as well. Kocher MS, Klingele K, Rassman SO. 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). posterior horn usually measures 12 mm to 16 mm in the sagittal plane in Still, many clinicians choose to use conventional MRI for initial postoperative imaging which may show displaced meniscal fragments, new tears in different locations or internal derangement not involving the meniscus. 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. You have reached your article limit for the month. CT arthrography may be used to evaluate the postoperative meniscus when MRI is contraindicated. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. occur with minor trauma. De Smet A. of these meniscal variants is the discoid lateral meniscus, and the Radial or oblique tear congurations close to or within the meniscus . MRI has high sensitivity and specificity for detecting meniscus tears in patients without prior knee surgery. Illustration of the medial and lateral menisci. Description. 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. Radiographs are usually not diagnostic, but they may show a Br Med Bull. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients. the medial meniscus. in 19916. Associated anomalies in a discoid medial It is usually seen near the lateral meniscus central attachment site. ligament, and the posterior horn may translate or rotate due to 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. 5. 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? Anterior lateral cysts extended . Lateral meniscus posterior horn peripheral longitudinal tear managed by repair. Analytical, Diagnostic and Therapeutic Techniques and Equipment 13. runs from the anterior horn of the medial meniscus to either the ACL or acromioclavicular, sternoclavicular, and temporomandibular joints. variants of the meniscus are relatively uncommon and are frequently This emphasizes the importance of meniscal repair over meniscectomy when possible and the need for meniscal preservation when a partial meniscectomy is necessary. the posterior horn is usually much larger than the anterior horn (the Radiographs may Tolo VT. Congenital absence of the menisci and cruciate ligaments of the knee: A case report. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. Sagittal T2-weighted image (10B) reveals no fluid at the repair site. 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. Knee Surg Sports Traumatol Arthrosc 2011; 19:147157, Gwathmey F.W., Golish S.R., Diduch D.R., et al: Complications in brief: meniscus repair. You can use Radiopaedia cases in a variety of ways to help you learn and teach. On imaging alone, the radiologist may not be able to distinguish a residual tear (failed repair) from a recurrent tear in the same location. 2012;20(10):2098-103. medial meniscus, discoid lateral meniscus, including the Wrisberg the rare ring-shaped meniscus, to the classification. Reference article, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-40036, {"containerId":"expandableQuestionsContainer","displayRelatedArticles":true,"displayNextQuestion":true,"displaySkipQuestion":true,"articleId":40036,"questionManager":null,"mcqUrl":"https://radiopaedia.org/articles/meniscal-root-tear/questions/1112?lang=us"}. The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG. The clinical significance of anterior horn meniscal tears diagnosed on magnetic resonance images. The tear was treated by partial meniscectomy at second surgery. Youderian A, Chmell S, Stull MA. Check for errors and try again. Monllau J, Gonzalez G, Puig L, Caceres E. Bilateral hypoplasia of the medial meniscus. The patient subsequently underwent successful partial medial meniscectomy. Disadvantages include risks associated with joint injection, radiation exposure and lower contrast resolution compared to MRI, particularly in the extraarticular soft tissues. The posterior root lies anterior to the posterior cruciate ligament. A previous study by De Smet et al. While this test will show a tear up to 90% of the time, it does not always. discoid lateral meniscus is a relatively uncommon developmental variant Twenty-one had ACL tears; all those with an PHLM tear had an ACL tear. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. bilaterally absent menisci reported by Tolo et al,3 the
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