What are the symptoms of a meniscus tear? what does it mean when a mri says a displacement at the meniscus root? does that cause a knee to lock?

Knee Pain&Swelling: Both anterior and posterior meniscal roots are the sites where the knee meniscus attaches to the tibial plateau (tibial bone). A tear tend to cause knee pain and swelling of the knee, especially in acute injuries. Displaced tears can cause mechanical symptoms such as clicking or joint locking during motion of the knee joint. Sometimes, there is an associated sensation of the knee giving away.

Giving way: Meniscal tears usually cause mechanical instability. The primary symptom is buckling or giving out. A displaced meniscus can cause the knee to lock. The meniscal root is where it attaches either in the front or back of the knee. Depending on your age it can be repaired or removed but is almost always a surgical treatment. See a good orthopedic surgeon.