Role of Magnetic Resonance Imaging in the Diagnosis of Posterior Medial Meniscal Root Tear of the Knee

The knee joint is one of the most important joints in the human body responsible for weight-bearing and a group of complex movements during ordinary life activities and even in vigorous sports making it susceptible to different traumatic injuries.Knee pain is considered as one of the most common complaints of patients presenting to clinical practitioners.There are many structures within the knee which can cause pain. By far, one of the most common causes of knee pain is a meniscus tear.The meniscus is the most important cushion in the knee; It plays an important bio mechanical role in axial load distribution of the knees. If the meniscus is injured and the cushioning is lost, arthritis and pain can occur.Menisci can tear due to traumatic injury or degenerative wear, 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. They often tend to be radial tears extending into the root.The medial meniscal posterior root tear can occur especially in middle-aged or older patients who have a single event of posteromedial painful popping sensation during light activities.Magnetic resonance imaging is well established as the best imaging modality for evaluating a patient with suspected meniscal pathology, involving the medial meniscal posterior horn root.In recent years, posterior meniscal root tears have received increasing attention in both Arthroscopic and Magnetic resonance study. All sequences of Magnetic resonance imaging should be reviewed, but T2 weighted coronal sections should provide the best visualization of the posterior roots. The Magnetic resonance findings of a medial meniscal posterior radial root tear are shortening or absence of the root (ghost sign) on sagittal images and a vertical fluid cleft with truncation sign and features of meniscal extrusion on coronal images.

It is very important to avoid errors in diagnosing meniscal root tears. So interpreting Magnetic resonance examinations of the knee need to be aware of the attachments of the menisci and to understand the normal variations in meniscal anatomy that may resemble a meniscal tear.

Tears of the meniscal root are relatively uncommon, occurring in 2.2% - 9.8% of patients undergoing Magnetic resonance imaging of the knee.However, it is important that these tears be diagnosed as several complications of meniscal root tear, including meniscal extrusion, secondary osteoarthritis, and subchondral insufficiency fracture.