What Exactly IS a Meniscus?

Damage to the meniscus of the knee is a relatively common orthopedic injury.  Chances are you know a friend who has damaged one of theirs or your doctor suspected or found such an injury in your own knee.  Despite the frequency, the menisci’s function and anatomy are not well understood by the general population.  Let’s take a moment to demystify the structure and function of the menisci, go over how their injuries can affect a person, and describe what you can expect if you need treatment:

So what IS a meniscus and what does it do?  Let’s start by taking a look at this image:

(Photo credit: https://www.researchgate.net/figure/Menisci-of-the-knee-and-common-tear-patterns_fig2_280872427

FIGURE 2 Menisci of the knee and common tear patterns.Contrarily, there are studies which repudiate these results. In a prospective diagnostic accuracy study of a cluster of physical examination tests (Thessaly’s, Apley’s, McMurray’s and joint line …www.researchgate.net


The menisci are the two ring-like structures sitting on the lower bone in the diagram (the tibia/shin bone).  You have two in each knee and they act like a pair of cups that help hold the femur (thigh bone) as your knee bends and straightens.  They work to make sure the two bones work together by making a secure, but semi-flexible surface for them to articulate with.

How can they get injured?  It’s no surprise that we rely on our legs a lot throughout the day.  The meniscus is designed to withstand all the different types of forces associated with normal movement, but every tissue has its limits.  A sharp turn too far in one direction (whether from falling down or from twisting too fast playing sports) could end up tearing some of the tissue that makes up your menisci (can happen to either meniscus or both, but it is more common in the medial or inner meniscus).

Can a meniscus heal by itself?  The short answer is, “it depends.”  The meniscus has an excellent supply on blood on the outside rim of each “cup,” but a very poor blood supply in the deeper portion of the cup.  What that means is that a smaller tear on that outer portion will probably heal on its own with some exercise, but a deeper tear will need surgery to fix the problem.

What will happen if my doctor thinks I have a tear?  In most situations, the doctor will want you to start exercise with a physical therapist once a tear is suspected.  If it’s a small tear, the therapy on its own will resolve the problem, but if it is a larger tear, the exercise will still be helpful to prepare for any upcoming surgery.  A doctor will typically request an MRI after a few weeks of therapy if symptoms haven’t reduced and will then review what kind of procedure they recommend.

How does exercise help my meniscus?  Every joint in your body relies on its mechanical framework AND its surrounding muscles for stability, and the knee is no exception.  If your muscles are weak or lack tone, they will not help provide stability to your joints as well as they could if they were strong.  When that happens, your bones and joints have to accept more strain than they otherwise would have to.  Thankfully, muscle strength is something we can influence in the clinic with targeted exercise proscribed by a physical therapist.

That being said, not all knee pain indicates a torn meniscus and a physical therapist or orthopedic doctor can help identify the differences between the various types of injuries.  Whether you have seen the doctor and have a script for therapy or whether you just want to get your knee examined by an expert, call our staff at 609-738-3143 for any inquiries.