Does only a MRI confirm a meniscus tear? Is there any other test to confirm that? Locking knee joint when sitting and raise the knee straight

It's the best. A meniscus does not show on an x-ray. The history and physical exam can really help make the diagnosis. An arthrogram, dye and air injected into the knee used to be used to help decide if a tear is present or not. Painful test, often inconclusive, and frankly just about a lost art. An MRI is fast, painless, and rarely wrong. Mris are usually done prior to suggesting surgery.
Alternative. Although not as good in the evaluation of the ligaments and soft tissues surrounding the knee, an arthrogram with CT is almost as good for the diagnosis of meniscal tears and articular damage as an MRI. I disagree with other comments indicating an arthrogram is a painful procedure. Done properly, it is usually not more painful than a flu shot. Google "DrNefcy.com" and click on arthrogram advice.
MRI is the best test. While ultrasound can show a meniscal tear it is has lower specificity and some false-positive diagnoses. Therefore, to avoid unnecessary arthroscopy an orthopedic surgeon will likely want an MRI for more detailed anatomical evaluation of the knee, confirmation of the diagnosis, as well as possibly finding additional pathology that might go undetected by ultrasound.

Related Questions

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. Read more...
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. Read more...

2years ago an Mri showed meniscus tear it wasn't treated at all and now knee is swelled and is extremely painful can't stand on it what can I do, wrong?

Quick fix and more. See an orthopedic surgeon or a physiatrist. They can evaluate the knee. If appropriate, they can drain the fluid and that will give you some immediate relief. Use ice and a compression wrap which will also reduce the pain a bit. Use a cane or crutches so that you take some weight off the affected leg and try to walk without stressing the other leg or your back! But see the Doc, get a diagnosis. Read more...