The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. History of medial meniscus posterior horn partial meniscectomy. Note that signal does not contact articular surface, The most common criterion for diagnosing meniscus tear on MRI is an increased signal extending in a line or band to the articular surface. to the base of the ACL or the intercondylar notch. 2006;239(3):805-10. 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. We use cookies to create a better experience. We will review the common meniscal variants, which Meniscal tears are common and often associated with knee pain. 3. Learn more. Torn lateral meniscus with superomedial and posterior flipped anterior horn. 1). 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). MRI failed to detect anterior horn injury of lateral meniscus in six (16.7%) cases, all of which were longitudinal fissure in the red zone. Collagen fibers are arranged for transferring compressive loads into circumferential hoop stresses, secured by radially oriented tie fibers. The shape of the meniscus is formed at the eighth week of Get unlimited access to our full publication and article library. menisci (Figure 8). The sensitivity of mri in detecting meniscal tears is generally good, ranging from 70-98%, with specificity in the same range in many studies. Monllau et al in 1998 proposed adding a fourth type, 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. 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. Discoid meniscus in children: Magnetic resonance imaging characteristics. Root tears are associated with a high risk for osteoarthritis. sagittal magnetic resonance (MR) images. Anatomic variability and increased signal change in this area are commonly mistaken for tears. 3: The Wrisberg variant, where the meniscus may have a normal And, some tears do not fill with contrast during arthrography. A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. The anterior and posterior sutures are shuttled down the tibial tunnel (arrowhead). 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). In the U.S., intraarticular injection of gadolinium-based contrast is off label. Surgery is useful if they are unstable and flipping in and out of the joint causing pain. 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. an adult), and approximately twice the size of the anterior horn on 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. mimicking an anterior horn tear. Direct MR arthrography requires intraarticular injection of 20-50 mL of dilute gadolinium contrast prior to imaging which distends the joint capsule and offers a high signal to noise ratio on T1-weighted images with contrast extension into the meniscal substance indicating a recurrent tear or an unhealed repair. 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. high fibula head and a widened lateral joint space.20 Several insertion of the medial meniscus (AIMM) has been described, and it is MR criteria are used to make the diagnosis. The condition is typically asymptomatic and, therefore, is infrequently diagnosed.14 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 Arthroscopy for Medial Meniscus Tears The decision to repair or remove the torn portion is made at the time of surgery. 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. show cupping of the medial tibial plateau, proximal medial tibial physis AJR American journal of roentgenology. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. ; Lee, S.H. The meniscus can separate from the joint capsule or tear through the allograft. 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. hypoplastic meniscus was not the cause of the patients pain, suggesting Close clinical correlation is advised before recommending surgery based on this finding alone. published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). Additionally, the postoperative complication of new extensive synovitis is apparent on the axial view (18D). tissue only persists at the edges, where differentiation into the Horizontal (degenerative) tears run relatively parallel the tibial plateau. On this page: Article: Epidemiology Pathology Radiographic features History and etymology Discoid lateral meniscus of the knee joint: Nature, mechanism, and operative treatment. 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. treatment for stable complete or incomplete types of discoid lateral small meniscus is also seen in the wrist joint. Shepard et al conclude that with a 74% false-positive rate, anterior horn tears should be treated surgically only if clinical correlation exists. Kocher MS, Klingele K, Rassman SO. Intact meniscal roots. Normal course and intensity of both cruciate ligaments. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. Bilateral hypoplasia of the medial meniscus has also been The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. It is often explained by fibers of the anterior cruciate ligament and the covering synovium . Development of the menisci of the human knee After failing conservative management with NSAIDs, PT, and activity modification, he underwent an MRI. MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. congenital anomalies affect the lateral meniscus, most commonly a MRI has high sensitivity and specificity for detecting meniscus tears in patients without prior knee surgery. The patient underwent a successful partial medial meniscectomy and was encouraged to seek low-impact exercise. CT arthrography is a recommended alternative for patients who are not MR eligible. 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. 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. are reported cases of complete absence of the medial meniscus as Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. The camera can visualize the meniscus and other structures within the knee. It is believed that discoid By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. Meniscal disorders: Normal, discoid, and cysts. 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). The most common include hypoplastic menisci, absent menisci, anomalous insertion of the separate the cavity. The ends of the anterior and posterior horns are firmly attached to the tibia at their roots. Am J Sports Med 2016; 44:625632, De Smet AA, Horak DM, Davis KW, Choi JJ. MRI of the knee is commonly indicated for evaluation of unresolved or recurrent knee pain following meniscal surgery. asymptomatic, although there is a greater propensity for discoid menisci Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. The medial meniscus covers 60% of the medial compartment. 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. Otherwise, the increased vascularity in children has sometimes led to false-positive reading of a meniscus tear. Knee Surg Sports Traumatol Arthrosc. Sagittal proton density (PD) images through normal medial (, The medial meniscus is larger, more oblong, and normally has a larger posterior horn than anterior horn in cross section. My own experience has been similar and I make it a policy not to recommend surgery based on this diagnosis alone without good clinical correlation. (1A) Proton density-weighted, (1B) T2-weighted, and (1C) fat-suppressed T1-weighted MR arthrographic sagittal images are provided. Grade 3 is a true meniscus tear and an arthroscope is close to 100 percent accurate in diagnosing this tear. The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). 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 . Sagittal T2-weighted image (10B) reveals no fluid at the repair site. from AIMM. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients. They are usually due to an acute injury [. There are 3 main types, according to the Watanabe classification:18. Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. 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. 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. variants of the meniscus are relatively uncommon and are frequently The trusted source for healthcare information and CONTINUING EDUCATION. Radial tears comprise approximately 15 % of tears in some surgical series [. 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. 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. 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. These tears are usually degenerative in nature and usually not associated with a discrete injury [. 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. 2019: Factors associated with bilateral discoid lateral meniscus tear in patients with symptomatic discoid lateral meniscus tear using MRi and X-ray Orthopaedics and Traumatology Surgery and Research: Otsr 105(7): 1389-1394 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 [. 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. Findings indicate an intact meniscus following partial meniscectomy with normal intrameniscal signal. The patient underwent an all-inside lateral meniscus repair. Wrisberg variant, the morphology of the meniscus may be normal, but the Disadvantages include risks associated with joint injection, radiation exposure and lower contrast resolution compared to MRI, particularly in the extraarticular soft tissues. What are the findings? 2006; 187:W565568. 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. 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 ]. Among these 26 studies of an LMRT . Posteroinferior displacement of the meniscal tissue (arrowheads) is also diagnostic of recurrent tear. Following meniscal allograft transplantation (Figure 17), complications occur in up to 21% of procedures, including allograft failure and progressive cartilage loss.19 Repeat operations occur in up to 35% of patients, 12% requiring conversion to total knee arthroplasty. The lateral meniscus is produced by the varus tension and tibial IR. These features constitute O'Donoghue unhappy triad. 70 year-old female with history of medial meniscus posterior horn radial tear. The medial compartment articular cartilage is preserved, and the meniscal body is not significantly extruded (16D). The sutures are tied over a cortical fixation device or Endobutton (short arrow) with the knee flexed at 90 to secure the root repair. morphology. Lee, J.W. Meniscal root tears are a form of radial tear that involves the central attachment of the meniscus (12a). for the ratio of the sum of the width of the anterior and posterior MRI showed posterior horn of the medial meniscus (PHMM) horizontal tear with early degenerative changes. 1 ). Lee S, Jee W, Kim J. Examination showed lateral joint line tenderness and a positive McMurray sign. Conventional MRI imaging correlates well with arthroscopic evaluation of the transplants for tears of the posterior and middle thirds of the meniscus allograft with a high sensitivity, specificity and accuracy, but results were poor for evaluation of the anterior third with a low specificity and accuracy.16 Allograft shrinkage and meniscus extrusion are common findings on postoperative MRI but do not always correlate with patient pain and function. AJR Am J Roentgenol. Type varus deformity (Figure 3). During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. Shepard and colleagues at UCLA specifically analyzed this by reviewing 947 consecutive MRIs. The MRI showed complete ACL tear with displaced bucket handle medial meniscus tear. The posterior root of the lateral meniscus (PRLM) attaches along the posterior aspect of the intercondylar eminence of the tibia (Fig. with mechanical features of clicking and locking. (middle third), or Type 3 (superior third; intercondylar notch) (Figure At the time the article was created Yuranga Weerakkody had no recorded disclosures. Copy. Longitudinal (longitudinal, peripheral-vertical) tears run parallel to the circumference of the meniscus along its longitudinal axis, separating the meniscus into central and peripheral portions (Fig. The discoid lateral-meniscus syndrome. Klingele KE, Kocher MS, Hresko MT, et al. Conventional MRI is useful for evaluation of posterior root morphology at the tibial tunnel fixation site, meniscal extrusion and articular cartilage. tear. They often tend to be radial tears extending into the meniscal root. Indications for meniscal repair typically include posttraumatic peripheral (red zone) longitudinal tears located near the joint capsule, ideally in younger patients (less than 40). Extrusion is commonly seen following root repair. MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn.

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