Both the medial and lateral menisci have a stout attachment at their very posterior aspects, which are called the root attachments. These root attachments are important because they hold the meniscus in place, provides stability to the circumferential hoop fibers of the meniscus, and prevents meniscal extrusion.
Description of Meniscal Root Tears
When there is a tear of the meniscal root, it has been demonstrated on biomechanical testing that it is equivalent to having the whole meniscus removed. Thus, a tear of the meniscal root is considered a very serious condition.
There are two different group of patients who suffer meniscal root tears:
• The first group consists of athletes in their 20s who sustain the tear with trauma. This could include an injury to the ACL, PCL, and other associated ligament combinations. In these circumstances, the meniscal root is commonly torn along with the ligament, and it is recommended to perform a concurrent meniscal root repair. Failure to repair the meniscal root tear in these circumstances can lead to the development of osteoarthritis, failure of a cruciate ligament reconstruction graft, and other problems further down the line.
• The second group of patients who commonly tear their meniscal root is adults in their 50s. The consequences of a meniscal root tear appear to be much more severe in this age group. A meniscal root tear, which can occur with minor or seemingly trivial trauma, with a pop in the back of their knee with deep flexion, squatting and lifting, and other activities, can be quite severe. It is in this group of patients for which the rapid development of osteoarthritis can occur. In some of these patients, rather significant bone swelling, insufficiency fractures, and the appearance of osteonecrosis (avascular necrosis), can obscure one to seeing that it was caused by meniscal root tear.
Meniscal Root Tear Meniscal root tears can be seen on coronal, axial and sagittal MRI views. On the sagittal view, as seen in Figure C, there is a “ghost sign” which is dindicative of meniscal root tear. A normal, healthy meniscus should look like a dark black triangle; however, as this figure shows the meniscus is much lighter or “ghosted” representing the root tear. (Click to Enlarge)
How to Read a MRI of a Meniscal Root Tear
Treatment for Meniscal Root Tears
The treatment of meniscal root tears in older patients can be very difficult. This is because they are not commonly diagnosed until the progression of arthritis is more severe. Due to the increasing knowledge that these tears can lead to rather progressive arthritis, one should consider an attempt at a meniscal root repair at the first signs of the development of pain and swelling with activities, which usually indicates the progression of arthritis, joint space narrowing, or any bony edema of the affected compartment on MRI scans. A concurrent distal femoral or proximal tibial osteotomy may also be indicated if the patient is malaligned to unload the affected compartment.
Meniscal root tears have only been noted as a significant pathology over the last 5 to 6 years. Research into the problem is ongoing. Our lab has noted that radial tears adjacent to the root attachment, known as a radial root tear, can also cause the same problems as a meniscal root avulsion of the attachment site. Our studies have also demonstrated that repairs of these radial root tears can restore fairly normal weightbearing characteristics and load sharing of the affected compartment. Thus, in properly selected patients, a radial root repair would also be indicated.
Patients who have a meniscal root repair need to be non-weightbearing for 6 weeks after surgery. Physical therapy is initiated on the first day after surgery. Patients are limited in moving their knees to 90 degrees of knee flexion for the first two weeks after surgery and then after this time they may increase their knee motion. At six weeks after surgery, a partial protective weight bearing program is initiated and patients may slowly wean off crutches when they can ambulate without a limp. The use of a stationary bike may be also started. Patients should avoid impact activities, deep squats, squatting and lifting, and sitting cross-legged for a minimum of 4 months after surgery to protect the meniscus root repair.
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