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. When interpreting MR images of the knee, it is important to assess for any change from the expected shape of the menisci. An MRI of plaintiff's left knee conducted in May 2018 demonstrated a complex 7 tear of the posterior horn of the lateral meniscus and a suspected horizontal tear of the anterior horn of the lateral meniscus. CT arthrography is a recommended alternative for patients who are not MR eligible. By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. 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 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. We will review the common meniscal variants, which One important reason for such discrepancies is a failure to understand the transverse geniculate ligament of the knee (TGL). 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. Kijowski et al. However, recognizing these variants is important, as they can Findings indicate an intact meniscus following partial meniscectomy with normal intrameniscal signal. Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. Exam showed a mild effusion and medial joint line tenderness. Clinical imaging. 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. Magnetic resonance imaging (MRI) is the most accurate imaging technique in the diagnosis of meniscal lesions and represents a standard tool in knee evaluation. 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 Pagnani M, Cooper D, Warren R. Extrusion of the Medial Meniscus. Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). While this test will show a tear up to 90% of the time, it does not always. Objectives: Low-field MRI at 0.55 Tesla (T) with deep learning image reconstruction has recently become commercially available. Renew or update your current subscription to Applied Radiology. Kim SJ, Moon SH, Shin SJ. Similarly, the postoperative meniscus is at increased risk for a recurrent tear either at the same or different location due redistribution of forces and increased stress on the articular surface. Knee Surg Sports Traumatol Arthrosc 2011; 19:147157, Gwathmey F.W., Golish S.R., Diduch D.R., et al: Complications in brief: meniscus repair. A meta-analysis of 44 trials. Because there is less pressure on the meniscus there, it is difficult to evaluate the anterior region of the meniscus. Unable to process the form. 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. On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. Figure 8: Medial oblique menisco-meniscal . Definite surfacing signal or distortion on only one image represents a possible tear. The patient failed conservative management of aspiration and cortisone injection. morphology. Interested in Group Sales? Tears MR imaging evaluation of the postoperative knee. collapse and widening of the medial joint space (Figure 7). structure on sagittal images on T1, proton density, and fat-saturated Extension to the anterior cortex of . Diagnosis - clinical presentation with exclusion of advanced knee osteoarthritis. No meniscal tear is seen, but the root attachment was also noted to be 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). They found that 76 (8%) of these indicated a tear of the anterior horn of either the medial or lateral meniscus. 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. The tear was treated by partial meniscectomy at second surgery. Of these patients treated nonoperatively, 6 had a diagnosis of an isolated anterior horn tear on MRI. Sagittal proton density-weighted image (8A) through the medial meniscus demonstrates signal extending to the tibial surface (arrow). When the cruciate In cases like this, MR arthrography is quite helpful. attachment of the posterior horn is the Wrisberg meniscofemoral (Tr. Problems encountered in a discoid medial meniscus are the same as a ligaments are absent, most commonly the anterior cruciate ligament (ACL) 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. Meniscal tears are common and often associated with knee pain. 1427-143. Discoid medial meniscus. tissue only persists at the edges, where differentiation into the 2012;199(3):481-99. menisci (Figure 8). 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. Fukuta S, Masaki K, Korai F. Prevalence of abnormal findings in magnetic resonance images of asymptomatic knees. However, many clinicians opt to use conventional MRI as the initial postoperative imaging study and reserve MR arthrography for equivocal cases. A tear of the ACL should also, in practice, not be a 6. History of longitudinal medial meniscus tear managed by meniscal repair (arrows). Ross JA,Tough ICK, English TA. 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. Anomalous 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. Volunteerism and Sports Medicine: Where do We Stand? Radiographs are usually not diagnostic, but they may show a 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). 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. Following partial meniscectomy, the knee is at increased risk for osteoarthritis. Get unlimited access to our full publication and article library. 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 . In the previously reported cases, as well as in this case, the This emphasizes the importance of baseline MRI comparison for evaluation of the postoperative meniscus.3. Anterior lateral cysts extended . The sagittal proton density-weighted image (13A) demonstrates linear high signal extending to the femoral and tibial surfaces (arrow). Neuschwander DC, Drez D Jr, Finney TP. Discoid lateral meniscus and the frequency of meniscal tears. of the distal femur and proximal tibia, and in the case report of 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. rim circumferentially, anteriorly, and posteriorly,19 which Development of the menisci of the human knee 2059-2066, Kinsella S.D., and Carey J.L. Conventional MRI is useful for evaluation of posterior root morphology at the tibial tunnel fixation site, meniscal extrusion and articular cartilage. Symptomatic anomalous insertion of the medial meniscus. both enjoyable and insightful. Surgical Outcomes Lysholm Score What are the findings? Best assessed on T2 weighted sequences. 9 The lateral meniscus is more loosely attached than the medial and can translate approximately 11mm with normal knee motion. joint: Morphologic changes and their potential role in childhood Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. Fellowship-trained musculoskeletal radiologists read 99% of the MRIs. The sutures are tied over a cortical fixation device or Endobutton (short arrow) with the knee flexed at 90 to secure the root repair. We use cookies to create a better experience. 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 published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). 300). Connolly B, Babyn PS, Wright JG, Thorner PS. Am J Sports Med. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. An intact meniscal repair was confirmed at second look arthroscopy. Increased signal intensity at the anterior horn of the lateral meniscus was seen on the images of seven of the 11 MR studies of the volunteers. 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. varus deformity (Figure 3). Report Youderian A, Chmell S, Stull MA. They often tend to be radial tears extending into the meniscal root. Lateral meniscus extrusion was present in six (23%) of 26 LMRTs and five (2.2%) of 231 patients with normal meniscus roots ( P < .001). 3. 4. medial meniscus, and not be confined to the ACL as seen in an ACL tear. The posterior root of the lateral meniscus (PRLM) attaches along the posterior aspect of the intercondylar eminence of the tibia (Fig. 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. Also, the inferior patella plica inserts on the (PubMed: 17114506), BakerJC, FriedmanMV, RubinDA (2018) Imaging the postoperative knee meniscus: an evidence-based review. {"url":"/signup-modal-props.json?lang=us"}, Weerakkody Y, Baba Y, Knipe H, et al. 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. Description. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. variant, and discoid medial meniscus. Discoid lateral meniscus was originally believed to result from an 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. This scan showed a radial MMT. 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). meniscal injury. CT arthrography may be used to evaluate the postoperative meniscus when MRI is contraindicated. Continuous meniscal tissue bridged the anterior and posterior horns of the lateral meniscus on 3 consecutive sagittal slices (Figure 1B). They often tend to be radial tears extending into the meniscal root. The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). Kaplan EB. and ACL tears can be mistaken for AIMM, but carefully tracing 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. 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 medial meniscus. Of the 14 athletes, 8 repairs were performed, 5 patients . 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. When bilateral, they are usually symmetric. Of the 54 participants, 5 had PHLM tears and 49 were normal. Anterior horn of the lateral meniscus: another potential pitfall in MR imaging of the knee. MRI has high sensitivity and specificity for detecting meniscus tears in patients without prior knee surgery. sagittal magnetic resonance (MR) images. Media community. Synopsis: In a consecutive series of nearly 1000 knee MRIs, there was a 74% false-positive rate for the diagnosis of anterior horn meniscal tears. On medial posterior root tears there is often 2: On posterior root radial tears of the lateral meniscus, the appearance may be similar to radial tears in other locations. The posterior root lies anterior to the posterior cruciate ligament. meniscus. It splits into two bands at the PCL, named Humphry(anterior to the PCL) and Wrisberg (posterior to the PCL). MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. The discoid lateral-meniscus syndrome. After failing conservative management with NSAIDs, PT, and activity modification, he underwent an MRI. to the base of the ACL or the intercondylar notch. Kijowski et al. the example shown (Figures 1 and 2), the entire medial meniscus is Medial meniscus posterior horn peripheral longitudinal tear treated with repair. least common is complete congenital absence of the menisci. He presented after a few months with symptoms of instability. The anterior horn inserts on the tibia and continues laterally to the anterior horn of the lateral meniscus via the transverse intermeniscal ligament. partly divides a joint cavity, unlike articular discs, which completely 2014; 43:10571064, McCauley TR. The fat-suppressed sagittal T1-weighted post arthrogram view (7C) demonstrates gadolinium extending into the meniscal substance. Anterior horn tear of the lateral meniscus in footballers with a stable knee is characterized by pain at the anterolateral aspect of the knee during knee extension, especially when kicking. Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. MRI of the knee is commonly indicated for evaluation of unresolved or recurrent knee pain following meniscal surgery. Weight-bearing knee X-rays showed a 50 % narrowing in the medial compartment. Lateral meniscus posterior horn peripheral longitudinal tear managed by repair. MRI Findings: Medial meniscus: Tear of the posterior horn seen to the inferior articular surface continuing into the posterior body and becoming more vertical. American Board of Orthopaedic Surgery Practice of the Orthopaedic Surgeon: Part-II, certification examination case mix. On MRI, longitudinal tears appear as a vertical line of abnormal signal contacting articular surface. Create a new print or digital subscription to Applied Radiology. trauma; however, other symptoms include clicking, snapping, and locking MR criteria for discoid lateral menisci are used for discoid medial The medial meniscus is asymmetrical with a larger posterior horn. proximal medial tibia was convex and the distal medial femoral condyle A Wrisberg type variant has not been documented in Menisci are present in the knees and the Nakajima T, Nabeshima Y, Fujii H, et al. Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images. be misinterpreted for more significant pathology on MRI. mesenchymal mass that differentiates into the tibia, femur, and 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. The anomalous insertion This high rate of success, however, may not apply to anterior horn tears, which occur much less commonly than posterior horn and meniscal body tears. insertion of the medial meniscus (AIMM) has been described, and it is In this section, the major patterns of tears are described and depicted in MRIs and arthroscopy images. 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. Case study, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-75066. Proper preoperative sizing of the allograft is critical for surgical success and usually performed with radiographs. 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. Discoid meniscus in children: Magnetic resonance imaging characteristics. Atypically thick and high location This article focuses on Variations in meniscofemoral ligaments at anatomical study and MR imaging. This emphasizes the importance of meniscal repair over meniscectomy when possible and the need for meniscal preservation when a partial meniscectomy is necessary. They are most frequently seen at the posterior horn of the medial meniscus. Disadvantages include increased cost, increased patient time, potential for adverse reactions to contrast agent compared to conventional MRI and lack of joint distention. The insertion site The example above illustrates marked degenerative changes caused by loss of meniscal function. 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. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. medial meniscus, discoid lateral meniscus, including the Wrisberg Intact meniscal roots. A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. In contrast to the medial meniscus, the posterior horn of the lateral meniscus is additionally secured by the meniscofemoral ligaments (MFL). snapping knee due to hypermobility. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. instance, tears of the lateral aspect of the anterior horn of the Radiographs may The ends of the anterior and posterior horns are firmly attached to the tibia at their roots. There is no universally accepted system for classifying meniscal tear patterns. This case features the following signs of meniscal tear: Case courtesy, Prof. Dr. Khaled Matrawy, Professor of radiology, Alexandria university, Egypt. Extrusion is commonly seen following root repair. 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. measurements of the posterior horn of the medial meniscus may vary, but Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). Dickhaut SC, DeLee JC. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. Grade II hyperintense horizontal signal of posterior horn of medial meniscus is noted. Indications for meniscal repair typically include posttraumatic peripheral (red zone) longitudinal tears located near the joint capsule, ideally in younger patients (less than 40). Brody J, Lin H, Hulstyn M, Tung G. Lateral Meniscus Root Tear and Meniscus Extrusion with Anterior Cruciate Ligament Tear. in 19916. (as previously described), meniscal cyst,26 discoid lateral meniscus in the same knee (Figure 9),25 and pathologic medial patella plica.27. during movement, and less commonly joint-line tenderness, reduced Tears in the red zone have the potential to heal and are more amenable to repair. was saddle shaped. 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. Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. 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 ]. 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. MRI features are consistent with torn lateral meniscus with flipped anterior horn superomedial and posterior, resting superior to the posterior horn. Another finding is the abnormal size or shape of the meniscus, which would indicate damaged surfaces [, To provide a greater degree of accuracy, De Smet advocated the two-slice-touch rule. To call a definite tear, one should see increased signal contacting the articular surface of the menisci on at least two images (sagittal or coronal). The clinical significance of anterior horn meniscal tears diagnosed on magnetic resonance images. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. The MRI also demonstrated moderate degenerative spurring at the lateral joint compartment, a large knee joint effusion with . ligaments and menisci causing severe knee dysplasia in TAR syndrome. are reported cases of complete absence of the medial meniscus as The lateral meniscus is produced by the varus tension and tibial IR. Bilateral complete discoid medial menisci combined with anomalous insertion and cyst formation. Normal shape and signal of the horns of the medial meniscus, with no evidence of tears or degenerations seen. The articular cartilage is well seen on the pre-operative sagittal proton density-weighted image (19B). 2. A 510, 210-pound 16-year-old male injured his left knee while kicking a football. At the time the article was created Yuranga Weerakkody had no recorded disclosures. The most important clinical concern at the time of MRI imaging is often high-grade articular cartilage loss. . In these cases, MR arthrography may provide additional diagnostic utility. 36 year old male with history of meniscus surgery 7 years ago. The purpose of our study was to determine if cysts of the ACL are the origin of cysts adjacent to the AHLM. Grade 3 is a true meniscus tear and an arthroscope is close to 100 percent accurate in diagnosing this tear. this may extend to to the mid body." is this a bucket tear? Rohren EM, Kosarek FJ, Helms CA. In Among these 26 studies of an LMRT . tear. The most commonly practiced of a case of discoid medial cartilage, with an embryological note. Menisci ensure normal function of the For partial meniscectomies involving 25% or more, conventional MRI has lower accuracy. And, some tears do not fill with contrast during arthrography. asymptomatic, although there is a greater propensity for discoid menisci The example above demonstrates the importance of baseline MRI comparison when evaluating the postoperative meniscus. It is located in the lateral portion of the knee interior of the knee joint. 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. They divide the meniscus into superior and inferior halves (Fig. The most widely used diagnostic modalities to assess the ligament injuries are arthroscopy and Magnetic Resonance Imaging (MRI). Radiographic knee dimensions in discoid lateral meniscus: Comparison with normal control. The menisci are C-shaped fibrocartilaginous structures composed of radial and circumferential collagen fibers that have several roles, including joint stabilization, load distribution, articular cartilage protection and joint lubrication. Each meniscus has three main parts, the back (posterior horn), middle (body), and front (anterior horn). Papalia R, Vasta S, Franceschi F, D'Adamio S, Maffulli N, Denaro V. Meniscal Root Tears: From Basic Science to Ultimate Surgery.

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