What is this popping in my knee? Some info on Meniscus Injuries.

Do you have any painful popping in your knee?  Especially when doing things around the house like stairs, squatting, or bending down?  There’s a good chance you could have a meniscus injury as it is one of the most common knee injuries around.  In Fact about 1 million meniscus surgeries are performed every year!  Despite the fact that there is increasing evidence that skipping the scalpel and doing therapy instead has better outcomes!  Who knew!?!  So read on and find out some interesting things about these little problematic guys.

Anatomy

The meniscus is split into two halves, the lateral (or outside part of the knee) and the medial (which is on the inside part of the knee).  Both halves sit on top of the tibia plateau which is the top of the main bone in our lower leg.  They are stuck onto that plateau similarly to how oysters or clams are stuck to their shell.  If we were to look at our meniscus from above they would look like to half moons.  

Meniscus injuries, meniscus anatomy

Knee Meniscal Anatomy. © Medical Stocks | Dreamstime.com

The lateral meniscus is a little bigger, more circular and thicker than the medial meniscus. It attaches to the PCL (posterior cruciate ligament) and due to it being more mobile during knee movements, it is less frequently injured than the medial meniscus.

On the other hand the medial meniscus is more of a C-shape, smaller, thinner, less mobile during knee movements, and it attaches to the ACL (anterior cruciate ligament).  Due to its size, shape, and location it is more prone to injuries than the lateral one.

Regardless of position both function to improve the load bearing, joint stability, and joint congruity of the knee.  They do this by increasing the joint contact area, decreasing the joint contact stresses, and protecting the articular cartilage of both the femur and the tibia.  Between the combination of shock absorption, lubrication, limitation of extreme movement and proprioception our meniscus are crucial for our daily function.

How do Meniscus Injuries Happen?

Meniscus injuries are more common in athletes, especially those that play in contact sports, but can occur in anyone regardless of age or activity level.  The most common way to injure your meniscus is by twisting your knee while your foot is still planted on the ground.   However, activities such as kneeling, squatting, lifting something heavy, or getting a direct blow to your knee when it is bent are other common ways of meniscus injuries.

Typically, people report feeling a pop when they injure their meniscus but for athletes that pop usually (>80% of the time) is associated with an ACL tear that will damage their meniscus.  You have to go back to our anatomy discussion to see how that works.  Remember, the medial meniscus is the smaller, thinner more fragile meniscus and of course it attaches directly to the ACL which is the most common knee ligament torn (Figures, right!?!)  Because of this association between the two structures meniscus injuries/tears are significantly more common in sports like football, basketball, soccer, baseball, and skiing; all sports where the knee can easily take a lateral blow while bent or where your foot can get stuck on the ground while your knee gets twisted.

Meniscus injuries, meniscus tear

Six of the most common meniscus tears seen in PT. ©Acer2020| iStock.com

This is all great information but what exactly happens to our meniscus when we injure it?  What exactly is a meniscus tear?  For that we asked Brian Ireland, PT, DPT, OCS, Cert MDT, CSCS, CGS, CKTP.  “Basically, if you were to look at our meniscus from the side it looks like a triangle, the outer border is thick and as it extends in towards the middle of the knee it slowly tapers together to a point.” he says.   “Typically twisting the femur on the tibia could pull up a portion of that thin inner section of the meniscus.  Sometimes that tear can create a flap in the meniscus.  When the knee bends that flap can get caught between two bones of the knee creating pain, popping, or both.”

Dr. Ireland continued to explain that the flap can get caught and ‘pop’ up between the bones when bending the knee but it can ‘pop’ back down when extending the knee.  “This is why people have a hard time wondering why their pain is not consistent.  It all depends on how much pressure they put on the flap to push it in the way of the knee working correctly, AND how often they are able to pull the flap out of the way” he said.  Additionally, the size of the tear can create a greater frequency of the pain, popping, and if the tear is large enough cause instability in the knee.

Symptoms of a Meniscus Injury

If you haven’t guessed already some of the more common symptoms people with a meniscus injury report are:

  • Knee popping, especially bending/straightening the knee
  • Knee locking, feeling like it gets stuck
  • Pain
  • Swelling
  • Instability, feeling like the knee is about to give out
  • Difficulty straightening the knee after being bent

Dr. Ireland says a lot of these symptoms are dependent on the size and location of the tear, which can lead to confusion for patients as to why there is such a variety of symptoms between different people’s meniscus injuries as well as differences in their own separate meniscus injuries.

Treatment of Your Meniscus Injury

meniscus injury, meniscus tear

Meniscus injury in an athlete after twisting her knee at practice. ©viewapart | stockphoto.com

Years ago, the slogan for a meniscal injury was “if it’s torn, take it out”.  This is because the outer part has blood vessels that provide nutrients but the inner, thinner part does not.  Since there is no blood supply to the more common inner part that has the tears the belief was to just remove it.

However, today that slogan is more like “save the meniscus”.  According to an article about modern meniscal treatments, written by Doral and colleagues,  “surgeons should strive not to operate in most cases, but to protect, repair or reconstruct, in order to prevent early development of osteoarthritis by restoring the native structure, function, and biomechanics of the meniscus.”  In English this means “don’t do surgery unless you have too in an effort to prevent arthritis; but if you do try to repair it first and if that doesn’t work, only take out the smallest amount possible to get the job done.”

Even better, another study funded by the NIH’s National Institute of Arthritis and Musculoskeletal and Skin Diseases found that many people can even avoid surgery by going to physical therapy!  This study has shown that those who underwent surgery and those who only did physical therapy had the same results after 12 months…The SAME RESULTS after 1 year!!!  Furthermore, they found that those who underwent surgery were under higher risk of developing arthritis later on in life due to having that surgery compared to those with much more conservative treatments such as physical therapy.

If you are having any symptoms described in this article or have a new pain, numbness, stiffness or tingling in any part of your body, arms or legs, contact us today!  With Direct Access in NJ we can get you in for an evaluation without you having to see your Doctor, probably quicker than you could get that appointment, while also saving you both time and money!  

Please, call us to schedule your evaluation at one of BeneFIT’s locations, Bridgewater (908.203.5200) or Chester (908.879.5700)  with one of our highly trained Doctors of Physical Therapy!

 

  • Doral, M. N., Bilge, O., Huri, G., Turhan, E., & Verdonk, R. (2018). Modern treatment of meniscal tears. EFORT open reviews, 3(5), 260–268. https://doi.org/10.1302/2058-5241.3.170067
  • Shimomura, K., Hamamoto, S., Hart, D. A., Yoshikawa, H., & Nakamura, N. (2018). Meniscal repair and regeneration: Current strategies and future perspectives. Journal of clinical orthopaedics and trauma, 9(3), 247–253. https://doi.org/10.1016/j.jcot.2018.07.008
  • Rath E, Richmond JCThe menisci: basic science and advances in treatmentBritish Journal of Sports Medicine 2000;34:252-257.
  • Makris, E. A., Hadidi, P., & Athanasiou, K. A. (2011). The knee meniscus: structure-function, pathophysiology, current repair techniques, and prospects for regeneration. Biomaterials, 32(30), 7411–7431. https://doi.org/10.1016/j.biomaterials.2011.06.037
  • Katz JN et al. Surgery versus Physical Therapy for a Meniscal Tear and Osteoarthritis. N Engl J Med. 2013 May 2;368(18):1675-84. PMID: 23506518. NCT00597012