Medial Meniscal Extrusion of Greater Than 3 Millimeters on Ultrasound Suggests Combined Medial Meniscotibial Ligament and Posterior Medial Meniscal Root Tears: A Cadaveric Analysis

Figure-4 Patient Positioning Increases Medial Meniscus Extrusion on Ultrasound in Patients With Posterior Medial Meniscus Root Tears of the Knee

“…Studies using open MRI have shown that MMPRT induces the pathological posterior extrusion of the MM in the knee-flexed position, 19 , 20 , 21 Farivar et al. 22 reported in the cadaveric study that the MME measured posterior to the MCL was greater than the MME measured anterior to the MCL at full extension and 30° of knee flexion after dissection of the posterior root of the MM. Therefore, it has been suggested that the meniscal extrusion associated with MMPRT is not simply a medial or posterior displacement from the articular surface, but rather a posteromedial rotational shift around the anterior root that is retained on the tibial plateau.…”

Measuring Technique for Meniscal Extrusion Using Ultrasound in the Setting of Posterior Medial Meniscal Root Tears

“…When both the posterior medial meniscal root and the medial meniscotibial ligament were sectioned, our cadaveric analysis demonstrated ME to be significantly greater in 30° versus 0° of flexion. 13 Using 3-dimensional digitization, Daney et al. 14 similarly reported greater ME at greater degrees of knee flexion.…”

“…Second, there have already been several studies evaluating ME at the posterior border of the MCL, which have found greater levels of ME in this area compared with measuring at other coronal cross sections along the medial meniscus. 13 , 14 …”

“…Our previous cadaveric analyses demonstrated a mean difference of only 0.25 mm when comparing ME values when measured with the 2 modalities. 13 , 17 The desire to use ultrasound for ME stems from its practicality, ability for weight-bearing measurements, and affordability. There have been several studies that have even reported its utility for measuring ME after medial meniscus allograft transplantation and identifying patients with lateral discoid menisci.…”

Meniscal extrusion consensus statement: A collaborative survey within the Meniscus International Network (MenIN) Study Group

“…The displacement of the meniscus induces biomechanical alterations in the knee joint, which have the potential to instigate progressive cartilage damage, ultimately leading to osteoarthritis (OA) [14]. Meniscal root lesions are frequently cited as a primary causative factor for meniscal extrusion [10,11], with surgical repair becoming a standard of care amongst specialized knee surgeons. However, the pathomechanism of meniscal extrusion is complex, with some authors reporting degenerative changes and other pathology affecting the meniscus stability leading to meniscal extrusion ultimately leading to meniscal root tear [12,18,19].…”