Lateral meniscal variant with absence of the posterior coronary ligament. A previous study by De Smet et al. . The camera can visualize the meniscus and other structures within the knee. menisci (Figure 8). Discoid meniscus in children: Magnetic resonance imaging characteristics. 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. Exam showed a mild effusion and medial joint line tenderness. There was no evidence of meniscal extrusion or a meniscal ghost sign (Fig. 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). The meniscus may also become hypertrophic. 6 months post-operative she had increased pain prompting follow-up MRI. The lateral meniscus is produced by the varus tension and tibial IR. Kaplan EB. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. Rohren EM, Kosarek FJ, Helms CA. AJR Am J Roentgenol 2009;193:515-523. Variations in meniscofemoral ligaments at anatomical study and MR imaging. Tears The posterior horn is always larger than the anterior horn. ligament, and the posterior horn may translate or rotate due to Sagittal T2-weighted image (18A) demonstrates high T2 fluid signal in the medial meniscus posterior horn consistent with a recurrent tear (arrow). However, the tear changes plane of orientation over its course. The self-reported complication rate for partial meniscectomy is 2.8% and meniscus repair is 7.6%. Bilateral hypoplasia of the medial meniscus has also been Normal Also, the inferior patella plica inserts on the Of the 14 athletes, 8 repairs were performed, 5 patients . include hypoplastic menisci, absent menisci, anomalous insertion of the We look forward to having you as a long-term member of the Relias A tear was found and the repair was revised at second look arthroscopy. 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. 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. Collagen fibers are arranged for transferring compressive loads into circumferential hoop stresses, secured by radially oriented tie fibers. Weight-bearing knee X-rays showed a 50 % narrowing in the medial compartment. Criteria for a recurrent tear after greater than 25% meniscectomy Definite surfacing T2 fluid signal (or high T1 signal isointense to intra-articular gadolinium on MR arthrography) on 2 or more images or displaced meniscal fragment.17 Definite surfacing fluid signal on only one image represents a possible tear. 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). pivoting). Clark CR, Ogden JA. variants of the meniscus are relatively uncommon and are frequently If a meniscus tear shows up on a MRI, it is considered a Grade 3. The anterior horn of the menisci, especially the lateral meniscus, is an area commonly confused on MRI. (Tr. This mesenchymal On examination, there was marked medial joint line tenderness and a large effusion. appearance.12 It is now believed that the knee develops from a The MRI revealed a vertical flap (oblique) tear of the medial meniscus. The medial meniscus is more tightly anchored than the lateral meniscus, allowing for approximately 5mm of anterior-posterior translation. Lateral meniscus extrusion was present in six (23%) of 26 LMRTs and five (2.2%) of 231 patients with normal meniscus roots ( P < .001). A This case features the following signs of meniscal tear: Case courtesy, Prof. Dr. Khaled Matrawy, Professor of radiology, Alexandria university, Egypt. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. {"url":"/signup-modal-props.json?lang=us"}, Weerakkody Y, Baba Y, Knipe H, et al. 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. If a horizontal tear involves a long segment of the meniscus, the central fragment may displace centrally from the peripheral portion of the meniscus [, Bucket handle tears (BHT) often cause pain and mechanical symptoms, such as locking, catching, and giving way [. On sagittal proton-density and T2-weighted images, this lesion was demonstrated by sensitive but nonspecific signs, such as the flipped meniscus . Shepard et al have done a nice job of telling us just how frequently this mistake can be made by fellowship trained musculoskeletal radiologists. Sagittal proton density-weighted (14A) and coronal T1-weighted (14B) images reveal a recurrent bucket-handle tear through the original repair site with typical findings of a displaced meniscal flap (arrow) into the intercondylar notch. the intercondylar notch, most commonly to the mid ACL, and less commonly 2a, 2b, 2c). Diagnostic performance is decreased following partial meniscectomy since the standard criteria used to diagnose a meniscus tear cannot be applied to the post-operative meniscus.3,4,5,6 Partial meniscectomy may distort the normal morphology of the meniscus and increased meniscal signal intensity may extend to the articular surface when a portion of the meniscus has been resected, simulating a tear. The example above demonstrates the importance of baseline MRI comparison when evaluating the postoperative meniscus. 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. ligaments are absent, most commonly the anterior cruciate ligament (ACL) 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). may simulate a peripheral tear (Figure 6).23 The only Anterior tibial marrow edema and organized trabecular fracture measuring 16 mm AP, 18 mm transverse. Fat suppressed sagittal T1-weighted MR arthrogram (5C) demonstrates gadolinium within the tear (arrow). Anomalous At 1 year, 5 of 6 were completely asymptomatic with the remaining patient minimally painful with no suggestion of meniscal symptoms. Arthroscopy evaluation found a lateral meniscus peripheral (red-white zone) longitudinal tear. ligaments and menisci causing severe knee dysplasia in TAR syndrome. During an arthroscopy, we have the choice of either repairing the meniscus tear or removing the torn piece. For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign. If the tear does not show, it is considered a Grade 1 or 2 and is not as serious. 6. The MRI sign of a radial tear is a linear, vertical cleft of abnormal high signal at the free edge (Fig. has shown that 41% of patients with a surgically confirmed torn post-operative meniscus had signal intensity within the meniscus extending into the articular surface which was lower than the signal intensity of gadolinium contrast.14 Like the presence of a line of intermediate T2 signal extending into the articular surface on conventional MRI, diagnosis of a torn post-operative meniscus on MRI arthrography is challenging when the intra-meniscal signal intensity is not as bright as gadolinium contrast. 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. Menisci are present in the knees and the On examination, the patient had medial joint line tenderness with positive McMurray test. Horizontal (degenerative) tears run relatively parallel the tibial plateau. 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 [. They found that 76 (8%) of these indicated a tear of the anterior horn of either the medial or lateral meniscus. Become a Gold Supporter and see no third-party ads. 4). Meniscal tears are common and often associated with knee pain. Recent evidence suggests that decreased extrusion may correlate to better clinical outcomes.18. Repair techniques include inside-out, outside-in or all-inside approaches. CT arthrography is a recommended alternative for patients who are not MR eligible. They were first described by M J Pagnaniet al. The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. However, recognizing these variants is important, as they can In the previously reported cases, as well as in this case, the The most widely used diagnostic modalities to assess the ligament injuries are arthroscopy and Magnetic Resonance Imaging (MRI). 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. Illustration of the transtibial pullout repair for a tear of the posterior horn medial meniscal root (arrow). This is a well-done study with clinical correlation and adequate follow-up. proximal medial tibia was convex and the distal medial femoral condyle 2006; 187:W565568. 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 . Radiology. This arises from the posterior horn of the lateral meniscus and attaches to the lateral aspect of the medial femoral condyle. Am J Sports Med. The sagittal proton density-weighted image (13A) demonstrates linear high signal extending to the femoral and tibial surfaces (arrow). Sometimes T2 signal in a healed tear may look similar to fluid. Generally, Discoid medial meniscus. 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. It splits into two bands at the PCL, named Humphry(anterior to the PCL) and Wrisberg (posterior to the PCL). History of longitudinal medial meniscus tear managed by meniscal repair (arrows). Description. Kim SJ, Moon SH, Shin SJ. The MFL was not observed in five (19%) of 26 studies of an LMRT. 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 What is a Grade 3 meniscus tear? At the time the article was created Yuranga Weerakkody had no recorded disclosures. As a result, the accuracy rate of diagnosis by MRI is 83.3%. American Board of Orthopaedic Surgery Practice of the Orthopaedic Surgeon: Part-II, certification examination case mix. collapse and widening of the medial joint space (Figure 7). Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. 800-688-2421. Continuous meniscal tissue bridged the anterior and posterior horns of the lateral meniscus on 3 consecutive sagittal slices (Figure 1B). The trusted source for healthcare information and CONTINUING EDUCATION. Dickhaut SC, DeLee JC. At least one meniscofemoral ligament is present in 7093 % Of knees The patient underwent a successful partial medial meniscectomy and was encouraged to seek low-impact exercise. 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. Knee Surg Sports Traumatol Arthrosc 2011; 19:147157, Gwathmey F.W., Golish S.R., Diduch D.R., et al: Complications in brief: meniscus repair. Most horizontal tears extend to the inferior articular surface. The lateral meniscus attaches to the popliteus tendon and capsule via the popliteomeniscal fascicles at the posterior horn and to the medial femoral condyle by the meniscofemoral ligaments. Examination showed lateral joint line tenderness and a positive McMurray sign. Lateral meniscus posterior horn peripheral longitudinal tear managed by repair. 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. structure on sagittal images on T1, proton density, and fat-saturated of the meniscus. Neuschwander DC, Drez D Jr, Finney TP. Sagittal PD (. Longitudinal medial meniscus tear managed by repair (arrow). 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 On imaging alone, the radiologist may not be able to distinguish a residual tear (failed repair) from a recurrent tear in the same location. Considered a feature of knee osteoarthritis. : Complications in brief: arthroscopic partial meniscectomy. 1. Magnetic resonance imaging of the postoperative meniscus: resection, repair, and replacement. However, clinically significant tears that can mechanically impinge were unlikely to have been missed. does not normally occur.13. Singh K, Helms CA, Jacobs MT, Higgins LD. In this case, we can determine that there is a new tear in a different location. AJR Am J Roentgenol. 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. CT arthrography is recommended for patients with MRI contraindications or when extensive susceptibility artifact from hardware obscures the meniscus. Arthrofibrosis and synovitis are also relatively common. as at no time in development does the meniscus have a discoid 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. With age, increased connective tissue stiffness of the meniscus develops secondary to elastin degradation and collagen rigidification.2. Semin Musculoskelet Radiol 2005;9(2):11624, Chung KS, Ha JK, Ra HJ, Nam GW, Kim JG. sagittal magnetic resonance (MR) images. At the time the case was submitted for publication Mostafa El-Feky had no recorded disclosures. The example above illustrates marked degenerative changes caused by loss of meniscal function. normal knee. occur with minor trauma. MR imaging and MR arthrography for diagnosis of recurrent tears in the postoperative meniscus. An intact meniscal repair was confirmed at second look arthroscopy. A tear of the ACL should also, in practice, not be a Kim SJ, Choi CH. congenital absence of the cruciate ligaments. Of these patients treated nonoperatively, 6 had a diagnosis of an isolated anterior horn tear on MRI. The medial meniscus covers 60% of the medial compartment. Wrisberg variant, the morphology of the meniscus may be normal, but the The insertion site Posterior meniscal root repairs: outcomes of an anatomic transtibial pull-out technique. A Wrisberg type variant has not been documented in Monllau J, Gonzalez G, Puig L, Caceres E. Bilateral hypoplasia of the medial meniscus. Imaging characteristics of the It is often explained by fibers of the anterior cruciate ligament and the covering synovium . Tachibana Y, Yamazaki Y, Ninomiya S. Discoid medial meniscus. History of a longitudinal medial meniscus tear managed by repair and concurrent ACL reconstruction. of these meniscal variants is the discoid lateral meniscus, and the Radiographs are usually not diagnostic, but they may show a These findings are also frequently associated with genu ; Lee, S.H. The anterior and posterior sutures are shuttled down the tibial tunnel (arrowhead). 1427-143. Regardless of the imaging protocol chosen for evaluation of the postoperative meniscus, optimal imaging interpretation includes: The normal MRI appearance after partial meniscectomy is volume loss and morphologic change, commonly truncation or blunting of the meniscal free edge. An intact meniscal repair was confirmed at second look arthroscopy. Concise, to-the-point text covers MRI for the entire musculoskeletal system, presented in a highly templated format. Indications for meniscal repair typically include posttraumatic peripheral (red zone) longitudinal tears located near the joint capsule, ideally in younger patients (less than 40). They often tend to be radial tears extending into the meniscal root. The medial meniscus is asymmetrical with a larger posterior horn. 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.
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