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The meniscus is a section of cartilage that absorbs impacts to the knee joint. The medial and lateral meniscus are particularly prone to pain either due to injury or degeneration. This video reviews the symptoms and diagnostic process for a knee meniscus tear.
Knee meniscus tears is one of the common causes of knee pain. The meniscus is basically the shock absorber within the knee. And you can tear either the medial (the inside) meniscus or the lateral meniscus. The inside meniscus is the more common one to be injured.
There are two general ways in which a meniscus becomes torn. Either there can be an acute injury, such as a twisting injury, a sports injury where you didn’t have pain, you did something, got hit, you twisted, you turned, and all of a sudden there’s this painful reaction because you’ve torn the meniscus. Or—and this is more common in folks as they get a little bit on with life in their 50s, 60s, 70s, 80s and beyond—there can be more of a degenerative tear within the meniscus, where there is no frank tear but just over time it has started to tear somewhat.
Meniscus pain, depending on which meniscus you tear, will either usually be on the inside of the knee, can be the entire knee, the outside of the knee.
The diagnosis of a knee meniscus tear begins with a history and a physical examination. The history is going to be important to ask questions such as the onset of injury, the mechanism of the onset of injury, where the pain is, what kind of pain is going on, when the pain is the worst, and what kinds of things makes the pain better.
On physical exam, often the joint line will be quite tender with a meniscus tear. And there are certain provocative maneuvers, like McMurray’s and Apley’s, different maneuvers that the physician will do in order to elicit pain that more generally comes from a meniscus. Although while these physical exam maneuvers tend to be relatively sensitive, meaning that if you have a meniscus, they tend to be positive, they are relatively non-specific, also, which means that people who don’t have a meniscus tear may also have a positive response to these provocative maneuvers. So those tests certainly lead you down the road toward the diagnosis, although they’re not necessarily definitive for the diagnosis.
Sometimes when a meniscus tear is suspected, an MRI will be ordered. And on the MRI you can see a meniscus tear, like we’ve talked about with other musculoskeletal problems. A meniscus tear can be there and not necessarily be causing the pain. So you take all of your imaging studies, with an MRI of the knee just like you would with an MRI of your back, you take the MRI findings with a grain of salt and put it into the context of the entire picture.