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300). About KOL ; Learn more about our technology and how more and more universities, research organizations, and companies in all industries are using our data to lower their costs. congenital absence of the cruciate ligaments. MR imaging evaluation of the postoperative knee. measurements of the posterior horn of the medial meniscus may vary, but 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. 2013;106(1):91-115. 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. {"url":"/signup-modal-props.json?lang=us"}, El-Feky M, Flipped meniscus - anterior horn lateral meniscus. as at no time in development does the meniscus have a discoid The lateral meniscus is produced by the varus tension and tibial IR. It is usually seen near the lateral meniscus central attachment site. Best assessed on T2 weighted sequences. Again, this emphasizes the importance of accurate history, prior imaging and operative reports. Kelly BT, Green DW. Note the symmetrical shape of the lateral meniscus (left) with similar size of the anterior and posterior horns. attachment of the posterior horn is the Wrisberg meniscofemoral 2008;191(1):81-5. Indirect MR arthrography is less commonly used and relies on excretion of intravascular gadolinium into the joint through synovial cells after intravenous administration of gadolinium contrast 20-90 minutes prior to the MRI exam. The sensitivity of mri in detecting meniscal tears is generally good, ranging from 70-98%, with specificity in the same range in many studies. Disadvantages include increased cost, increased patient time, potential for adverse reactions to contrast agent compared to conventional MRI and lack of joint distention. 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. Because there is less pressure on the meniscus there, it is difficult to evaluate the anterior region of the meniscus. medial meniscus are extremely uncommon and should not be a diagnostic The anterior root of the lateral meniscus attaches to the tibia, just lateral to the midline and posterior to fibers of the anterior cruciate ligament (ACL). On examination, there was marked medial joint line tenderness and a large effusion. 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. For DSR inquiries or complaints, please reach out to Wes Vaux, Data Privacy Officer, the rare ring-shaped meniscus, to the classification. Monllau et al in 1998 proposed adding a fourth type, Atypically thick and high location At the time the article was last revised Yahya Baba had no financial relationships to ineligible companies to disclose. (middle third), or Type 3 (superior third; intercondylar notch) (Figure . By continuing to use our site, you consent to the use of cookies outlined in our Privacy Policy. 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. 3. Sagittal proton density-weighted image (9A) demonstrates no high signal abnormality. There There was no history of a specific knee injury. Radiology. St. Louis County's newspaper of politics and culture A displaced longitudinal tear is a "bucket handle" tear. Wrisberg variant, the morphology of the meniscus may be normal, but the The avulsed anterior horn of the lateral meniscus is flipped over and situated above the posterior horn. 2006; 187:W565568. As such, I can count on my hands the number of isolated anterior horn meniscal tears that I have seen at surgery that I felt were symptomatic over the past 5 years. Exam showed a mild effusion and medial joint line tenderness. Type 1: A complete slab of meniscal tissue with complete tibial coverage. problem in practice. Grade II hyperintense horizontal signal of posterior horn of medial meniscus is noted. No paralabral cyst. Both the healed peripheral tear and the new central tear were proved at second look arthroscopy. In some patients, hyperintense signal may persist at the repair site on conventional MRI for several years and is thought to represent granulation tissue. However, clinically significant tears that can mechanically impinge were unlikely to have been missed. MRIs of BHT may have several characteristic appearances including (1) fragment in the notch sign; (2) double anterior horn sign, in which there is an additional meniscal fragment in the anterior joint on top of the native anterior horn; (3) the absent bow tie sign; (4) the double PCL sign, in which the centrally displaced fragment lies just anterior and parallel to the PCL giving the appearance of two PCLs; and (5) the coronal truncation sign, in which the free edge of the meniscal body appears clipped off on coronal images (Fig. Arthroscopy evaluation found a lateral meniscus peripheral (red-white zone) longitudinal tear. asymptomatic, although there is a greater propensity for discoid menisci 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. Of these patients treated nonoperatively, 6 had a diagnosis of an isolated anterior horn tear on MRI. occur with minor trauma. : Complications in brief: arthroscopic partial meniscectomy. 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. Because this is a relatively new procedure, few studies have been dedicated to MRI evaluation of postoperative root repair. 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. There are 3 main types, according to the Watanabe classification:18. Meniscal root tear. This injury is biomechanically comparable to a total meniscectomy, leading to compromised hoop stressesresulting in decreased tibiofemoral contact area and increased contact pressures in the involved compartment.These changes are detrimental to the articular cartilage and . 2. On MRI, they exhibit abnormal horizontal linear signal contacting the inferior articular surface near the free edge or less commonly the superior surface. It is believed that discoid Collagen fibers are arranged for transferring compressive loads into circumferential hoop stresses, secured by radially oriented tie fibers. This is a critical differentiation because the latter represents meniscal tears that can be Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. Pain is typically medial and activity-related (e.g. joint: Morphologic changes and their potential role in childhood of the distal femur and proximal tibia, and in the case report of The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. include hypoplastic menisci, absent menisci, anomalous insertion of the Arthroscopy for Medial Meniscus Tears The decision to repair or remove the torn portion is made at the time of surgery. On the sagittal fat-suppressed T2-weighted image (7B), fluid extends into the tear. An abnormal shape may indicate a meniscal tear or a partial meniscectomy. 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. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. > 20% ratio of meniscus to tibia on the coronal image; Minimum diameter 14-15 mm on a midcoronal image; 75% The clinical significance of anterior horn meniscal tears diagnosed on magnetic resonance images. Proper preoperative sizing of the allograft is critical for surgical success and usually performed with radiographs. Radial Meniscal Tear: Pearls May be degenerative or traumatic, vertical, millimeters in size, on the inner edge of the lateral meniscus more commonly than the medial meniscus The medial meniscus is asymmetrical with a larger posterior horn. MRI showed posterior horn of the medial meniscus (PHMM) horizontal tear with early degenerative changes. Of those 31 patients who underwent arthroscopic examination, there were only 8 true anterior horn tears (26% true positive rate) and 18 had normal or intact menisci in all zones. | 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. Comparison of Postoperative Antibiotic Regimens for Complex Appendicitis: Is Two Days as Good as Five Days? 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. Radial or oblique tear congurations close to or within the meniscus . 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. This mesenchymal Complex or deep radial tears were found in three of five cases of lateral meniscus extrusion and normal root. 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. Unable to process the form. 2a, 2b, 2c). meniscal diameter. medial meniscus, discoid lateral meniscus, including the Wrisberg There are The meniscal repair is intact. Generally, discoid lateral meniscus is a relatively uncommon developmental variant No meniscal tear is seen, but the root attachment was also noted to be The posterior cruciate ligament is intact. Biologic augmentation with application of exogenous fibrin clot or growth factors may be combined with the repair to promote healing. MR imaging is useful for evaluation of many possible complications following meniscal surgery. The MRI showed complete ACL tear with displaced bucket handle medial meniscus tear. Anterior horn of the lateral meniscus: another potential pitfall in MR imaging of the knee. At the time the case was submitted for publication Mostafa El-Feky had no recorded disclosures. Variations in meniscofemoral ligaments at anatomical study and MR imaging. Most studies have shown increased accuracy for direct and indirect MR arthrography compared to conventional MRI for partial meniscectomies of 25% or more.16. CT arthrography may be used to evaluate the postoperative meniscus when MRI is contraindicated. A new longitudinal tear has occurred more centrally in the meniscus (arrowhead) with linear high signal extending to the tibial and femoral surfaces as well as fluid signal and gadolinium contrast in the defect. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. Considered a feature of knee osteoarthritis. ADVERTISEMENT: Supporters see fewer/no ads. Diagnosis - clinical presentation with exclusion of advanced knee osteoarthritis. 1991;7(3):297-300. The common insertion of the anterior cruciate ligament (ACL) and the AHLM root may provide a pathway for disease. posterior horn of the medial meniscus include a triangular hypointense pretzels dipped in sour cream. Most horizontal tears extend to the inferior articular surface. The most common Concise, to-the-point text covers MRI for the entire musculoskeletal system, presented in a highly templated format. We use cookies to create a better experience. Sagittal proton density-weighted image (8A) through the medial meniscus demonstrates signal extending to the tibial surface (arrow). A recurrent tear was proved at second look arthroscopy. Thus, the loss of the lateral meniscus can often lead to rather rapid onset of osteoarthritis. Meniscal tears were found on MRI or arthroscopy in all 28 patients with a lateral cyst overlying the body or posterior horn of the lateral meniscus, whereas a tear was found on MRI or arthroscopy in only 14 (64%) of 22 patients with cysts adjacent to or extending to the lateral meniscus anterior horn (p = 0.006). MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. When it involves the posterior root, medial root tears are easier to diagnose than lateral root tears. Normal menisci. MRI has high sensitivity and specificity for detecting meniscus tears in patients without prior knee surgery. Both ligaments attach distally to the posterior horn of the lateral meniscus and contribute to posterior drawer stability . However, many clinicians opt to use conventional MRI as the initial postoperative imaging study and reserve MR arthrography for equivocal cases. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients. A 510, 210-pound 16-year-old male injured his left knee while kicking a football. Sagittal T2-weighted image (10B) reveals no fluid at the repair site. diagnostic dilemma, as the AIMM band will be seen to extend to the 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 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 is no telling how much this error rate will change for radiologists less experienced with MRI. Most patients are asymptomatic, but injury to the meniscus can Am J Sports Med. A meta-analysis of 44 trials. The patient underwent meniscal repair but had recurrent pain prompting repeat MRI 8 months post-operative. MR criteria for discoid lateral menisci are used for discoid medial (PubMed: 17114506), BakerJC, FriedmanMV, RubinDA (2018) Imaging the postoperative knee meniscus: an evidence-based review. Normal The example above illustrates marked degenerative changes caused by loss of meniscal function. from AIMM. for the ratio of the sum of the width of the anterior and posterior 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). On the fat-supressed proton density-weighted coronal (17A) and axial (17B) images, notice the trapazoidal shaped bone bridge (arrow) placed in the tibial slot with menscal allograft attached at the anterior and posterior roots. On MR arthrography, (12B), gadolinium extends through the repair site indicating a tear. . Objective Parameniscal cysts have a very high association with meniscal tears in all locations except the anterior horn lateral meniscus (AHLM). Zonal variation is also seen in the density of meniscus cells and their phenotypes with a chondrocytic inner zone and fibroblastic outer zone. Copy. However, the tear changes plane of orientation over its course. hypermobility. There is no universally accepted system for classifying meniscal tear patterns. Illustration of the transtibial pullout repair for a tear of the posterior horn medial meniscal root (arrow). Interested in Group Sales? A 23-year-old female presented with a 2-month history of catching and pain in the knee when arising from a squatting position. posterior horn usually measures 12 mm to 16 mm in the sagittal plane in The anterior and posterior sutures are shuttled down the tibial tunnel (arrowhead). Normal This case features the following signs of meniscal tear: absent bow tie appearance of the lateral meniscus ghost meniscus: empty location of the anterior horn of the lateral meniscus The shape of the meniscus is formed at the eighth week of The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. The medial meniscus covers 60% of the medial compartment. MRI: When you tear your meniscus, a magnetic resonance imaging (MRI) scan will show the injury as white lines on black. They are most frequently seen at the posterior horn of the medial meniscus. Continuous meniscal tissue bridged the anterior and posterior horns of the lateral meniscus on 3 consecutive sagittal slices (Figure 1B). 800-688-2421. Grade 3 is a true meniscus tear and an arthroscope is close to 100 percent accurate in diagnosing this tear. Tachibana Y, Yamazaki Y, Ninomiya S. Discoid medial meniscus. Horizontal (degenerative) tears run relatively parallel the tibial plateau. found that the absence of a line of increased signal through the meniscus extending to the articular surface on proton density and T2-weighted images was a reliable MRI finding for an untorn post-operative meniscus with 100% sensitivity. Heron, D, Bonnard C, Moraine C,Toutain A. Agenesis of cruciate intra-articular structures at 8 weeks gestation. AJR American journal of roentgenology. is in fact reducing the volume of the meniscus and restoring a normal MRI plays a critical role in influencing the treatment decision and enables information that would obviate unnecessary surgery including diagnostic arthroscopy. However, recognizing these variants is important, as they can Menisci ensure normal function of the The same imaging criteria (as for the case of greater than 25% partial meniscectomy), the presence of fluid signal on T2-weighted or contrast extending into the meniscal substance is used to diagnose a recurrent tear. 6 months post-operative she had increased pain prompting follow-up MRI. Am J Sports Med 2016; 44:625632, De Smet AA, Horak DM, Davis KW, Choi JJ. Results: Arthroscopic examination of the anterior horn of the lateral meniscus in all 22 patients was normal. As DLM is a congenital anomaly, the ultrastructural features and morphology differ from those of the normal meniscus, potentially leading to meniscal tears. does not normally occur.13. Clin Orthop Relat Res 2013; 471: pp. snapping knee due to hypermobility. 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. Bilateral complete discoid medial menisci combined with anomalous insertion and cyst formation. 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. What is your diagnosis? Resnick D, Goergen TG, Kaye JJ, et al. They were first described by M J Pagnaniet al. Meniscal tears are common and often associated with knee pain. Clinical imaging. Special thanks to David Rubin, MD for providing several cases used in this web clinic. medial meniscus, and not be confined to the ACL as seen in an ACL tear. 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. Midterm results in active patients. be misinterpreted for more significant pathology on MRI. Am J Sports Med 2017; 45:884891, Zaffagnini S, Grassi A, Marcheggiani Muccioli GM, et al. ligaments are absent, most commonly the anterior cruciate ligament (ACL) Disadvantages include patient discomfort, increased cost, physician time needed for the procedure and radiation exposure during fluoroscopy. 5. mobility, and a giving-way sensation.11, 15, 16 A high percentage of cases present with an associated meniscal tear and peripheral rim instability.9,16,17 Although discoid lateral meniscus is commonly bilateral, symptoms tend to occur on one side.15 It is characterized by an excess of meniscal tissue with a slab-like configuration in the 2 most common forms (Figure 5). Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. Associated anomalies in a discoid medial 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. The posterior root lies anterior to the posterior cruciate ligament. 4. runs from the anterior horn of the medial meniscus to either the ACL or MRI of the knee is commonly indicated for evaluation of unresolved or recurrent knee pain following meniscal surgery. After failing conservative management with NSAIDs, PT, and activity modification, he underwent an MRI. The anterior meniscofemoral ligament (Humphrey ligament) attaches proximally on the medial femoral condyle, inferior to the PCL insertion. Torn lateral meniscus with superomedial and posterior flipped anterior horn. The MRI also demonstrated moderate degenerative spurring at the lateral joint compartment, a large knee joint effusion with . The trusted source for healthcare information and CONTINUING EDUCATION. Papalia R, Vasta S, Franceschi F, D'Adamio S, Maffulli N, Denaro V. Meniscal Root Tears: From Basic Science to Ultimate Surgery. The self-reported complication rate for partial meniscectomy is 2.8% and meniscus repair is 7.6%. FSE T2-weighted images, with a slab-like appearance on coronal images. 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. of the menisci can be summarized as providing: Clark and Ogden studied the natural development of the menisci in the 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. Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. meniscal injury. In the previously reported cases, as well as in this case, the For information on new subscriptions, product This emphasizes the importance of baseline MRI comparison for evaluation of the postoperative meniscus.3. The patient had a recent new injury with increased pain. No gadolinium extension into the meniscus on fat-suppressed sagittal T1-weighted (9B) post arthrogram view. Recent evidence suggests that decreased extrusion may correlate to better clinical outcomes.18. 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.