A 510, 210-pound 16-year-old male injured his left knee while kicking a football. The condition is typically asymptomatic and, therefore, is infrequently diagnosed.14 Menisci ensure normal function of the MR arthrogram fat-suppressed sagittal T1-weighted image (11C) shows no gadolinium in the repair. Pre-operative fat supressed coronal proton density-weighted image (19A) demonstates a posterior root radial tear (arrow). Arthroscopy revealed a horizontal tear of PHMM, and a partial medial meniscectomy was performed. The incidence was calculated based on arthroscopic findings, and the potential secondary signs of meniscal ramp tears were evaluated on MRI. (middle third), or Type 3 (superior third; intercondylar notch) (Figure Meniscal transplant is usually reserved for patients younger than 50 years who have normal axial alignment. attachment of the posterior horn is the Wrisberg meniscofemoral 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. You can use Radiopaedia cases in a variety of ways to help you learn and teach. They often tend to be radial tears extending into the meniscal root. Examination of the knee showed a mild effusion, 1+ Lachman, positive Pivot shift, and mild tenderness to both medial and lateral joint lines. The sagittal proton density-weighted image (2A) demonstrates increased signal intensity at the periphery of the medial meniscus posterior horn (arrow) but no fluid signal on the sagittal T2-weighted image (2B) and no gadolinium extension into this area on the MR arthrogram sagittal fat-suppressed T1-weighted arthrographic image (2C) consistent with a healed repair. Normal with mechanical features of clicking and locking. is in fact reducing the volume of the meniscus and restoring a normal There is a medial and a lateral meniscus. There was no history of a specific knee injury. Discoid lateral meniscus was originally believed to result from an 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. The posterior cruciate ligament is intact. The sutures are tied over a cortical fixation device or Endobutton (short arrow) with the knee flexed at 90 to secure the root repair. Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), Posterior Instability and Labral Pathology, Imaging Evaluation of the Painful or Failed Shoulder Arthroplasty, Other Entities: PLRI, HO, Triceps, and Plica, MRI-Arthroscopy Correlations in the Overhead Athlete, Acetabular Fossa, Femoral Fovea, and the Ligamentum Teres. Anterior horn lateral meniscus tear A female asked: Mri: "macerated anterior horn lateral meniscus with inferiorly surfacing tear. may simulate a peripheral tear (Figure 6).23 The only What is a Lateral Meniscus Tear? meniscal diameter. Longitudinal medial meniscus tear managed by repair (arrow). Of the 14 athletes, 8 repairs were performed, 5 patients . 4. 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 Rohren EM, Kosarek FJ, Helms CA. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. An alternative way of fastening the allograft to the donor knee involves harvesting the meniscus with a small bone plug attached to each root and then securing the plugs within osseous tunnels drilled in the recipient tibia. On MRI, they resemble radial tears, with a linear cleft of abnormal signal seen at the free edge. 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. normal knee. 9 The lateral meniscus is more loosely attached than the medial and can translate approximately 11mm with normal knee motion. 800-688-2421. Tear between 1-4 cm vertical tear red-red meniscal root <40 yo Maybe concominant ACL surgery . 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. This case is almost identical to the previous case with a different clinical history. Seventy-four cases of bucket-handle tears (mean age, 27.2 11.3 years; 38 medial meniscus and 36 lateral meniscus; 39 concomitant anterior cruciate ligament (ACL) reconstruction) were treated with arthroscopic repair from June 2011 to August 2021. Magnetic resonance imaging (MRI) is the most accurate imaging technique in the diagnosis of meniscal lesions and represents a standard tool in knee evaluation. 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. Studies on meniscus root tears have investigated the relationship of osteoarthritis and an anterior cruciate ligament tear. discoid lateral meniscus, including a propensity for tears to occur and in 19916. A Wrisberg type variant has not been documented in posterior horn of the medial meniscus include a triangular hypointense 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. Source: Shepard MF, et al. during movement, and less commonly joint-line tenderness, reduced 2005; 234:5361. 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. Neuschwander DC, Drez D Jr, Finney TP. 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. Lateral meniscus tears of the posterior root are a common concomitant injury to anterior cruciate ligament (ACL) tears [6, 16, 20]. Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, VA, is Editor of Sports Medicine Reports. A tear of the lateral meniscus can occur from a sudden injury, or from chronic wear and overload. Both ligaments attach distally to the posterior horn of the lateral meniscus and contribute to posterior drawer stability . The torn edges are aligned, and stable fixation applied with sutures or bioabsorbable implants at approximately 5 mm intervals. Anterior tibial marrow edema and organized trabecular fracture measuring 16 mm AP, 18 mm transverse. Lateral meniscal variant with absence of the posterior coronary ligament. 2019: Factors associated with bilateral discoid lateral meniscus tear in patients with symptomatic discoid lateral meniscus tear using MRi and X-ray Orthopaedics and Traumatology Surgery and Research: Otsr 105(7): 1389-1394 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. Discoid medial menisci are much less common than discoid lateral menisci,24 and they may be bilateral. The patient underwent a successful partial medial meniscectomy and was encouraged to seek low-impact exercise. Bilateral hypoplasia of the medial meniscus has also been 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. Healed peripheral medial meniscus posterior horn repair and new longitudinal tear in a different location. 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 ]. The posterior root of the medial meniscus attaches to the tibia, just anterior and medial to the posterior cruciate ligament (PCL). Lee, J.W. Shepard et al have done a nice job of telling us just how frequently this mistake can be made by fellowship trained musculoskeletal radiologists. 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. The lateral meniscus is more circular, and its anterior and posterior horns are nearly equivalent in size in cross section. The fat-suppressed sagittal T1-weighted post arthrogram view (7C) demonstrates gadolinium extending into the meniscal substance. Bilateral discoid medial menisci: Case report. Repair techniques include side-to-side repair, stabilization with suture anchors, and the transtibial pull-out technique (figure 4).12. The anterior and posterior meniscofemoral ligaments (Humphrey and Wrisberg respectively) are commonly present with one or both found in 93-100% of patients. 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. Presentation - Middle-older aged individuals, non-traumatic, progressive onset of pain. (PubMed: 17114506), BakerJC, FriedmanMV, RubinDA (2018) Imaging the postoperative knee meniscus: an evidence-based review. 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. Lee S, Jee W, Kim J. Radiographs may 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. 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. congenital anomalies affect the lateral meniscus, most commonly a Lateral meniscus bucket handle tears can produce the double anterior horn sign or double ACL sign. 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. In these cases, thin-section or well-placed axial images confirm that the tear is not a simple radial tear but rather a vertical flap tear (Fig. CT arthrography is recommended for patients with MRI contraindications or when extensive susceptibility artifact from hardware obscures the meniscus. Lateral Meniscus: Anatomy The lateral meniscus is seen as a symmetric bow tie in the sagittal plane on at least one or two sections before it divides into two asymmetric triangles near the midline. According to one source, they are thought to account for ~10% of all arthroscopic meniscectomies 5. Longitudinal lateral meniscus tear status post repair (arrow). Repair techniques include inside-out, outside-in or all-inside approaches. The meniscus is two crescent-shaped, thick pieces of cartilage that sit in the knee between the tibia and the femur. Posterior meniscal root repairs: outcomes of an anatomic transtibial pull-out technique. 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. They maintain a relatively constant distance from the periphery of the meniscus [. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. The meniscus root plays an essential role in maintaining the circumferential hoop tension and preventing meniscal displacement. In contrast to the medial meniscus, the posterior horn of the lateral meniscus is additionally secured by the meniscofemoral ligaments (MFL). The example above illustrates marked degenerative changes caused by loss of meniscal function. the intercondylar notch, most commonly to the mid ACL, and less commonly to tear. Illustration of the transtibial pullout repair for a tear of the posterior horn medial meniscal root (arrow). 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 Clin Orthop Relat Res 2013; 471: pp. For root tears in general, sagittal imaging may demonstrate a meniscal ghost sign. posterior horn usually measures 12 mm to 16 mm in the sagittal plane in 3. RESULTS. Shepard and colleagues at UCLA specifically analyzed this by reviewing 947 consecutive MRIs. MRI Findings: Medial meniscus: Tear of the posterior horn seen to the inferior articular surface continuing into the posterior body and becoming more vertical. Type 1 is most common, and type The incidence of lateral meniscus posterior root tears was approximately 4 times higher than of medial meniscus posterior root tears in both primary (12.2% vs 3.2%) and revision (20.5% vs 5.6%) ACLRs. 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). Their conclusion that one should not perform surgery unless clinical correlation exists with effusions, mechanical catching or locking, or the failure to respond to nonoperative measures I believe is a good recommendation that we can all follow. The MRI showed complete ACL tear with displaced bucket handle medial meniscus tear. medial meniscus, and not be confined to the ACL as seen in an ACL tear. Following partial meniscectomy, the knee is at increased risk for osteoarthritis. At least one meniscofemoral ligament is present in 7093 % Of knees The congenitally absent meniscus appears to influence the development 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. Variations in meniscofemoral ligaments at anatomical study and MR imaging. is affected. Concise, to-the-point text covers MRI for the entire musculoskeletal system, presented in a highly templated format. Diagnosis of recurrent meniscal tears: prospective evaluation of conventional MR imaging, indirect MR arthrography, and direct MR arthrography. in this case were attributed to an anterior cruciate ligament tear Clinical imaging. There is no telling how much this error rate will change for radiologists less experienced with MRI. Weight-bearing knee X-rays showed a 50 % narrowing in the medial compartment. A Radiology. Suprapatellar plica noticed, with no related cartilaginous erosions.