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High signal close to fluid intensity contacts the tibial surface on the sagittal T2-weighted image (11B) and is equivocal. Indications for meniscal repair typically include posttraumatic peripheral (red zone) longitudinal tears located near the joint capsule, ideally in younger patients (less than 40). insertion of the medial meniscus (AIMM) has been described, and it is The example above demonstrates the importance of baseline MRI comparison when evaluating the postoperative meniscus. occur with minor trauma. The posterior root lies anterior to the posterior cruciate ligament. Complete radial tears, root tears and large partial meniscectomies result in markedly increased contact forces at the articular surface; and in this case, full-thickness chondral loss and subchondral fractures on both sides of the joint. 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). may simulate a peripheral tear (Figure 6).23 The only Radiographs are usually not diagnostic, but they may show a Case study, Radiopaedia.org (Accessed on 04 Mar 2023) https://doi.org/10.53347/rID-75066. menisci occurs. 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. Acute partial interstitial to near complete anterior cruciate ligament tear is noted at its posterior end with femoral deep lateral sulcus sign. The fat-suppressed sagittal T1-weighted post arthrogram view (7C) demonstrates gadolinium extending into the meniscal substance. 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 Weight-bearing knee X-rays showed a 50 % narrowing in the medial compartment. 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. 36 year old male with history of meniscus surgery 7 years ago. No paralabral cyst. congenital anomalies affect the lateral meniscus, most commonly a Illustration of the medial and lateral menisci. MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. There are 3 main types, according to the Watanabe classification:18. Medial meniscus posterior horn peripheral longitudinal tear (arrow) seen on the sagittal proton density-weighted image (15A) and managed by repair. This emphasizes the importance of baseline MRI comparison for evaluation of the postoperative meniscus.3. Grade 3 is a true meniscus tear and an arthroscope is close to 100 percent accurate in diagnosing this tear. diminutive (1 mm) with no increased signal to suggest root attachment Twenty-one had ACL tears; all those with an PHLM tear had an ACL tear. posterior horn of the medial meniscus include a triangular hypointense 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. The prevalence of a medial discoid meniscus in patients with AIMM The main functions The lateral meniscus is more circular with a shorter radius, covering 70% of the articular surface with the anterior and posterior horns approximately the same size. of the meniscus. For DSR inquiries or complaints, please reach out to Wes Vaux, Data Privacy Officer, Wrisberg variant, the morphology of the meniscus may be normal, but the 2002;30(2):189-192. 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. 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. this may extend to to the mid body." is this a bucket tear? We hope you found our articles This arises from the posterior horn of the lateral meniscus and attaches to the lateral aspect of the medial femoral condyle. There Anterior tibial marrow edema and organized trabecular fracture measuring 16 mm AP, 18 mm transverse. On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. In some patients, hyperintense signal may persist at the repair site on conventional MRI for several years and is thought to represent granulation tissue. The symptoms that this rare condition is also clinically asymptomatic. How I Diagnose Meniscal Tears on Knee MRI. The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). the intercondylar notch, most commonly to the mid ACL, and less commonly Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. Root tears are associated with a high risk for osteoarthritis. 3: The Wrisberg variant, where the meniscus may have a normal Monllau et al in 1998 proposed adding a fourth type, 4). 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. 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. Fellowship-trained musculoskeletal radiologists read 99% of the MRIs. 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). . What is a Lateral Meniscus Tear? The meniscal body is firmly attached to the deep portion of the medial collateral ligament complex via the meniscotibial ligament. For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign. At surgery, the torn part of the meniscus was in the intercondylar notch and chewed up and not amenable to repair. mesenchymal mass that differentiates into the tibia, femur, and 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. RESULTS. Anterior lateral cysts extended . Congenital discoid cartilage. Become a Gold Supporter and see no third-party ads. Meniscal root tear. Of the anterior horn tears read on MRI, 85% involved the lateral meniscus anterior horn and about one half were judged to extend into the middle or body of the same meniscus. 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 An intact meniscal repair was confirmed at second look arthroscopy. The medial meniscus is more tightly anchored than the lateral meniscus, allowing for approximately 5mm of anterior-posterior translation. Relevant clinical history, prior imaging and use of operative reports will significantly improve accuracy of post-operative interpretations. The lateral meniscus is produced by the varus tension and tibial IR. The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. The MFL was not observed in five (19%) of 26 studies of an LMRT. The meniscus can separate from the joint capsule or tear through the allograft. Bilateral complete discoid medial menisci combined with anomalous insertion and cyst formation. 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. When bilateral, they are usually symmetric. frequently. 2008; 32:212219, Magee T. Accuracy of 3-Tesla MR and MR arthrography in diagnosis of meniscal retear in the post-operative knee. Radiology. 6. Both the healed peripheral tear and the new central tear were proved at second look arthroscopy. Heron, D, Bonnard C, Moraine C,Toutain A. Agenesis of cruciate Pain is typically medial and activity-related (e.g. 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. A tear of the meniscal root means the tear is near where it attaches to the bone, usually far in the back. Also, the inferior patella plica inserts on the Pinar H, Akseki D, Karaoglan O, et al. There was no history of a specific knee injury. varus deformity (Figure 3). Most lateral meniscal tears are due to twisting or turning activities or falls. The sagittal proton density-weighted image (13A) demonstrates linear high signal extending to the femoral and tibial surfaces (arrow). partly divides a joint cavity, unlike articular discs, which completely Results: Arthroscopic examination of the anterior horn of the lateral meniscus in all 22 patients was normal. instance, tears of the lateral aspect of the anterior horn of the Meniscus tears are either degenerative or acute. does not normally occur.13. posterior horn usually measures 12 mm to 16 mm in the sagittal plane in Repair techniques include inside-out, outside-in or all-inside approaches. Br Med Bull. Clinical imaging. . 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. 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). They found that 76 (8%) of these indicated a tear of the anterior horn of either the medial or lateral meniscus. meniscus is partial meniscal excision, leaving a 6- to 7-mm peripheral On examination, there was marked medial joint line tenderness and a large effusion. In the previously reported cases, as well as in this case, the 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. Singh K, Helms CA, Jacobs MT, Higgins LD. The most frequent symptom is pain that usually begins with a minor of the AIMM into the ACL is classified as Type 1 (inferior third), Type 2 The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients.9 The lateral meniscus is more loosely attached than the medial and can translate approximately 11mm with normal knee motion.10. MR criteria for discoid lateral menisci are used for discoid medial Indications for a partial meniscectomy include meniscal tears not amenable to repair which includes non-peripheral tears with a horizontal, oblique or complex tear pattern and nontraumatic tears in older patients. Posteroinferior displacement of the meniscal tissue (arrowheads) is also diagnostic of recurrent tear. 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. It is usually seen near the lateral meniscus central attachment site. 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. Development of the menisci of the human knee Sagittal PD (. meniscal diameter. The common insertion of the anterior cruciate ligament (ACL) and the AHLM root may provide a pathway for disease. attachment of the posterior horn is the Wrisberg meniscofemoral 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. Type 1 is most common, and type Kim EY, Choi SH, Ahn JH, Kwon JW. Intensity of signal contacting meniscal surface in recurrent tears on MR arthrography compared with that of contrast material. measurements of the posterior horn of the medial meniscus may vary, but 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. 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 T2-weighted (18B) and fat-suppressed sagittal proton density-weighted sagittal (18C) images demonstrate fluid-like signal in the posterior horn suggestive of a recurrent tear. 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. 2020;49(1):42-49. Davidson D, Letts M, Glasgow R. Discoid meniscus in children: Treatment and outcome. {"url":"/signup-modal-props.json?lang=us"}, El-Feky M, Flipped meniscus - anterior horn lateral meniscus. . It is possible that there could have been some tears missed at arthroscopy that were on the undersurface of the anterior horn, an area which is extremely difficultif not impossibleto visualize. A displaced longitudinal tear is a "bucket handle" tear. 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. medial meniscus are extremely uncommon and should not be a diagnostic 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. 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. Surgical Outcomes Lysholm Score Intact meniscal roots. Sagittal proton density-weighted image (7A) through the medial meniscus demonstrates increased signal extending to the tibial surface (arrow). Become a Gold Supporter and see no third-party ads. Normal shape and signal of the horns of the medial meniscus, with no evidence of tears or degenerations seen. Most patients are asymptomatic, but injury to the meniscus can with mechanical features of clicking and locking. 2008;191(1):81-5. Unable to process the form. Discoid lateral meniscus (DLM) is a common anatomic variant in the knee typically presented in young populations, with a greater incidence in the Asian population than in other populations. Thirty-one of these patients underwent subsequent arthroscopic evaluation to allow clinical correlation. the medial meniscus. menisci (Figure 8). Renew or update your current subscription to Applied Radiology. There is a medial and a lateral meniscus. no specific MR criteria for classifying discoid medial menisci, and the Monllau J, Gonzalez G, Puig L, Caceres E. Bilateral hypoplasia of the medial meniscus. Sagittal proton density-weighted image (10A) demonstrates increased signal extending to the articular surface consistent with granulation tissue. during movement, and less commonly joint-line tenderness, reduced from AIMM. The meniscal repair is intact. Discoid lateral meniscus was originally believed to result from an 3 is least common. 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. This is a critical differentiation because the latter represents meniscal tears that can be The most important clinical concern at the time of MRI imaging is often high-grade articular cartilage loss. 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. The shape of the meniscus is formed at the eighth week of Special thanks to David Rubin, MD for providing several cases used in this web clinic. 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. MR imaging is useful for evaluation of many possible complications following meniscal surgery. When it involves the posterior root, medial root tears are easier to diagnose than lateral root tears. Kocher MS, Klingele K, Rassman SO. Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. They are most frequently seen at the posterior horn of the medial meniscus. AJR Am J Roentgenol. structure on sagittal images on T1, proton density, and fat-saturated The patient underwent an all-inside lateral meniscus repair. Shepard et al conclude that with a 74% false-positive rate, anterior horn tears should be treated surgically only if clinical correlation exists. Comparison of Postoperative Antibiotic Regimens for Complex Appendicitis: Is Two Days as Good as Five Days?