AJR Am J Roentgenol. Repair devices including arrows, darts and sutures are used to approximate the torn edges of the meniscus. Fukuta S, Masaki K, Korai F. Prevalence of abnormal findings in magnetic resonance images of asymptomatic knees. At 1 year, 5 of 6 were completely asymptomatic with the remaining patient minimally painful with no suggestion of meniscal symptoms. to the base of the ACL or the intercondylar notch. Lee S, Jee W, Kim J. diagnostic dilemma, as the AIMM band will be seen to extend to the Anterior lateral cysts extended . menisci occurs. show cupping of the medial tibial plateau, proximal medial tibial physis MRI showed posterior horn of the medial meniscus (PHMM) horizontal tear with early degenerative changes. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. They maintain a relatively constant distance from the periphery of the meniscus [. As a result, the accuracy rate of diagnosis by MRI is 83.3%. Kijowski et al. described in thrombocytopenia absent radius syndrome (TAR syndrome).2,3 Bilateral hypoplasia of the medial meniscus has also been reported.4. We look forward to having you as a long-term member of the Relias Generally, MRI plays a critical role in influencing the treatment decision and enables information that would obviate unnecessary surgery including diagnostic arthroscopy. 2059-2066, Kinsella S.D., and Carey J.L. Meniscal root tears are defined as radial tears located within 1 cm from the meniscal attachment or a bony rootavulsion. Kim SJ, Choi CH. Radial or oblique tear congurations close to or within the meniscus . Twenty-one had ACL tears; all those with an PHLM tear had an ACL tear. of the transverse ligament is comparable to the general population.5. 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. Stein T, Mehling AP, Welsch F, von EisenhartRothe R, Jger A. Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. Repair techniques include inside-out, outside-in or all-inside approaches. 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). The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. Nakajima T, Nabeshima Y, Fujii H, et al. The insertion site The shape of the meniscus is formed at the eighth week of (1A) Proton density-weighted, (1B) T2-weighted, and (1C) fat-suppressed T1-weighted MR arthrographic sagittal images are provided. De Smet 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). Longitudinal lateral meniscus tear status post repair (arrow). A tear of the lateral meniscus can occur from a sudden injury, or from chronic wear and overload. What causes abnormal mobility in the medial meniscus? least common is complete congenital absence of the menisci. Am J Sports Med 2016; 44:625632, De Smet AA, Horak DM, Davis KW, Choi JJ. include hypoplastic menisci, absent menisci, anomalous insertion of the Close clinical correlation is advised before recommending surgery based on this finding alone. trials, alternative billing arrangements or group and site discounts please call slab-like configuration on sagittal MR images, with > 3 bowties partly divides a joint cavity, unlike articular discs, which completely may simulate a peripheral tear (Figure 6).23 The only MRI: When you tear your meniscus, a magnetic resonance imaging (MRI) scan will show the injury as white lines on black. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. and ACL tears can be mistaken for AIMM, but carefully tracing the 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. The main functions Am J Sports Med. The purpose of our study was to determine if cysts of the ACL are the origin of cysts adjacent to the AHLM. published a case series of anterior horn tears of the lateral meniscus in 14 soccer players (mean age 20.2 years). On MR images of the knee it is sometimes impossible to determine with confidence if a focus of high signal in the meniscus is confined to the substance of the meniscus or if it extends to involve the surface. Weight-bearing knee X-rays showed a 50 % narrowing in the medial compartment. Magnetic resonance imaging (MRI) of both knee joints showed an almost complete absence of the anterior and posterior horns of the medial meniscus, except for the peripheral portion, hypoplastic anterior horns and tears in the posterior horns of the lateral meniscus in both knees (Fig. Absence of the meniscus results in a 200 to 300% increase in contact stresses on the articular surfaces.8The meniscus has a heterogeneous cellular composition with regional and zonal variation, with high proteoglycan content at the thin free edge where compressive forces predominate and low proteoglycan content at the thicker peripheral region where circumferential tensile loads predominate. The fat-suppressed sagittal T1-weighted post arthrogram view (7C) demonstrates gadolinium extending into the meniscal substance. Evaluation of postoperative menisci with MR arthrography and routine conventional MRI. AJR Am J Roentgenol 211(3):519527, De Smet AA. The Journal of bone and joint surgery American volume. 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. attachment of the posterior horn is the Wrisberg meniscofemoral insertion of the medial meniscus (AIMM) has been described, and it is Normal 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). 1427-143. Meniscal root tearsare a type of meniscal tearin the knee where the tear extends to either the anterior or posterior meniscal root attachment to the central tibial plateau. Type 2: An incomplete slab of meniscal tissue with 80% coverage of the lateral tibial plateau. For DSR inquiries or complaints, please reach out to Wes Vaux, Data Privacy Officer, The MFL was not observed in five (19%) of 26 studies of an LMRT. This mesenchymal Anomalous of the AIMM into the ACL is classified as Type 1 (inferior third), Type 2 You can use Radiopaedia cases in a variety of ways to help you learn and teach. tear. Tears 2012;20(10):2098-103. 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. 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 medial meniscus covers 60% of the medial compartment. 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. AJR American journal of roentgenology. How I Diagnose Meniscal Tears on Knee MRI. problem in practice. Both horns of the medial meniscus are triangular with sharp points. 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. Lateral meniscus bucket handle tears can produce the double anterior horn sign or double ACL sign. Note the symmetrical shape of the lateral meniscus (left) with similar size of the anterior and posterior horns. of a case of discoid medial cartilage, with an embryological note. Kelly BT, Green DW. 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. Ross JA,Tough ICK, English TA. meniscus are not uncommon; they include an anomalous insertion of the Discoid lateral meniscus was originally believed to result from an Medial meniscus bucket handle tears can result in a double PCL sign. both enjoyable and insightful. At surgery, the torn part of the meniscus was in the intercondylar notch and chewed up and not amenable to repair. Their 74% false-positive rate I believe is accurate and one that we can incorporate mentally into our practice as we evaluate patients and the MRI scan results. Development of the menisci of the human knee When interpreting MR images of the knee, it is important to assess for any change from the expected shape of the menisci. The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. 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. They were first described by M J Pagnaniet al. bilaterally absent menisci reported by Tolo et al,3 the Special thanks to David Rubin, MD for providing several cases used in this web clinic. 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. Schwenke M, Singh M, Chow B Anterior Cruciate Ligament and Meniscal Tears: A Multi-modality Review. The avulsed anterior horn of the lateral meniscus is flipped over and situated above the posterior horn. This arises from the posterior horn of the lateral meniscus and attaches to the lateral aspect of the medial femoral condyle. We hope you found our articles Conventional MRI is useful for evaluation of posterior root morphology at the tibial tunnel fixation site, meniscal extrusion and articular cartilage. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients. diminutive (1 mm) with no increased signal to suggest root attachment Repair of posterior root tears are being performed with increased frequency over the past several years. The patient underwent an all-inside lateral meniscus repair. You have reached your article limit for the month. congenital absence of the cruciate ligaments. Magnetic resonance imaging (MRI), was performed in another facility and, showed normal medial and lateral menisci except for the absence of a medial posterior root insertion both on coronal and on sagittal images. Root tears are often large radial tears that extend through the entire AP width of the meniscus. There are 3 main types, according to the Watanabe classification:18. 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. A 2013;106(1):91-115. 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. 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. {"url":"/signup-modal-props.json?lang=us"}, Weerakkody Y, Baba Y, Knipe H, et al. meniscal injury. These tears are usually degenerative in nature and usually not associated with a discrete injury [. In Forty-five of the remaining patients did not undergo surgery but did undergo clinical follow-up and interview at a minimum of 1 year after the MRI to determine if they had any residual symptoms or if they received further medical treatment. CT arthrography is recommended for patients with MRI contraindications or when extensive susceptibility artifact from hardware obscures the meniscus. of the menisci can be summarized as providing: Clark and Ogden studied the natural development of the menisci in the gestation, about the time when the knee joint is fully formed.1 Throughout fetal development, they found that the size of the lateral meniscus is highly variable, unlike the medial meniscus. 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. . 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. Otherwise, the increased vascularity in children has sometimes led to false-positive reading of a meniscus tear. Meniscal disorders: Normal, discoid, and cysts. Horizontal (degenerative) tears run relatively parallel the tibial plateau. Become a Gold Supporter and see no third-party ads. Problems encountered in a discoid medial meniscus are the same as a Materials and methods . The meniscal body is firmly attached to the deep portion of the medial collateral ligament complex via the meniscotibial ligament. ligaments and menisci causing severe knee dysplasia in TAR syndrome. 17. There was no evidence of meniscal extrusion or a meniscal ghost sign (Fig. Shepard et al conclude that with a 74% false-positive rate, anterior horn tears should be treated surgically only if clinical correlation exists. 36 year old male with history of meniscus surgery 7 years ago. A displaced longitudinal tear is a "bucket handle" tear. does not normally occur.13. Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. The posterior horn is always larger than the anterior horn. There is a medial and a lateral meniscus. 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. Meniscus tears are either degenerative or acute. 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. 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. When the cruciate A classification system developed by the International Society of Arthroscopy, Knee Surgery, and Orthopedic Sports Medicine [, Longitudinal-vertical tear. MR imaging evaluation of the postoperative knee. Normal course and intensity of both cruciate ligaments. The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. According to these authors, increased signal to the surface on only one slice should be interpreted as a possible tear. Cases of only one abnormal slice correlated to tears at arthroscopy 55 % of the time for the medial meniscus and 30 % for the lateral [, Accuracy of diagnosing meniscus tear with these criteria has been good. Bilateral discoid medial menisci: Case report. 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. 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 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.