Do you have knee pain, perhaps with knee popping or clicking? Dr. Bennett talks about the anatomy of the knee, and he describes the likely causes of knee pain, knee locking and knee clicking. He’s an experienced knee doctor and a Board Certified Orthopedic Surgeon and a Fellowship Trained Sports Medicine Specialist. with offices in Houston, near the Houston Galleria and Sugar Land, near First Colony Mall. You can make an appointment with Dr. Bennett by calling 281-633-8600 in Sugar Land and 713-234-3152 in Houston.
My name is Dr. J. Michael Bennett. I am a Board Certified orthopedic sports medicine specialist — welcome to my Whiteboard Series of patient education videos.
Today we’re going to discuss the causes of knee pain, which is a question we get quite a bit. When many patients come to our clinics, their primary complaint is, “My knee just popped, and now it’s swollen and hurts. What do I do?” We’re going to go over some things today regarding knee pain and a popping sensation in the knee and what exactly that means. If you’d like to learn about what’s involved in an orthopedic knee exam, please watch our video.
So first thing you’ll notice is usually your knee is going to be painful. You will feel or actually hear sometimes an audible pop in the knee usually associated with a twisting or turning motion or sometimes from a direct blow or impact. So real quickly we’re going to go over some of the basic anatomy of a knee. I’ve already drawn this on the whiteboard here.
This is your knee, and this is the femoral condyle, and this is the tibial plateau of the knee. The stabilizing structures of the knee are the medial collateral ligament, which is on the inside of the knee. I’ll show you here on the model as well. This is a small model but this is the medial collateral ligament in the inside of the knee. This is the lateral collateral ligament on the outside of the knee. These two ligaments stabilize the knee from what we call valgus stress and varus stress.
In the middle, you have your cruciate ligaments, which are criss-crossed ligaments. They’re called cruciates because they basically criss-cross each other to form a cross. They’re in the middle of the knee and actually control for the rotation. The most commonly injured cruciate is the anterior cruciate ligament, which is this ligament right here. And usually you’ll get a tear and it’s usually associated with the twisting, turning motion as well as the direct valgus or lateral impact, which will cause a pop in that ligament, as well as occasionally an injury or a pop in the medial collateral ligament, which is on the inside of the knee.
So most patients will say, “I got hit from the side. I felt a pop and then my knee became unstable,” so that would be an injury here to the medial collateral ligament on the inside, which is a stretching injury. And then a tearing injury on the anterior cruciate ligament, which is in the middle of the knee, that creates stability for rotation deformity so those are two things to consider if you do feel a pop, particularly after a high impact. That’s something to consider.
You should go see an orthopedic surgeon immediately. Ice the knee, keep it elevated. Try not to do any cutting, twisting and pivoting activities, but just go ahead and get evaluated by a physician just to confirm whether or not the ligament is injured.
Anther possibility for a pop in the knee and knee pain is a patient that comes in that describes a popping or a locking sensation in the knee. They usually don’t have a high impact injury and let’s just say they’re walking in the mall, or they do a twisting and turning rotation motion, or they’re playing tennis and all of a sudden their knee catches or gets stuck, and then it becomes very hard to straighten and it becomes painful until they get a pop.
That can mean that’s something’s actually getting caught in the joint itself, that’s keeping them from extending the knee and that oftentimes means it might be a cartilage or meniscus injury. The meniscus are two discs within the knee. There’s one disc in the inside, the medial ligament meniscus and then there’s a lateral meniscus. You can have a tear in either of those discs. They are actually cartilage discs, so this cartilage over time can get soft and all it can take is just a twisting motion, the catch can create a tear so the discs here…this is the medial meniscus, and this is the lateral meniscus. One meniscus on the inside and one on the outside of the knee joint, and you can have a tear right down the middle, like this, and on this view, looking at the knee straight on, like this, it looks like that.
If you look on the knee, straight down, from top down, like that, it looks like this so these are the meniscus. Sometimes you can get a tear on the inner one-third of the meniscus, like that, which would create a flap, or you can get a tear on the outer one-third, which can create a large flap. We call that a bucket handle tear, because it actually looks like a bucket handle when it flips up and gets caught in the joint because it gets stuck here. This whole piece of disc flips up into the joint and actually causes the knee to lock.
Depending on what type of tear it is, is going to determine your treatment. Some of these tears are repairable, some of them aren’t but then again, it’s up to your orthopedic surgeon to do a proper evaluation, get an MRI and determine what kind of a tear you have. Based on your activity status, your age, as well as the type of tear will determine the type of treatment you receive for that meniscus tear. So if you feel a painful locking sensation in the knee, the knee swells, you definitely need to be evaluated by an orthopedic surgeon just to make sure that there’s nothing serious going on within the knee, such as a meniscus tear.
The next possibility when it comes to locking or popping in the knee is a cartilage injury within the actual lining itself, which is along here. And this is actually a cartilage lining that you see here, the blue area of the joint and you can have cartilage flaps actually detach from this area and create a flap, or even create a little punch hole or a little crater within the cartilage itself. This is more chronic. These are more arthritic changes, because after you lose a portion of this cartilage, you have exposed bone underneath there and that’s basically wear and tear, but sometimes these can occur acutely as well from a fall or an injury because of an impaction injury occurring here.
So that can create actually a loose body, or a loose piece of cartilage that may be either hinged open like a flap, or a loose floating body within the joint and that little floating body can get stuck anywhere in the joint. And depending on where it is will determine how much knee pain you feel, whether or not your knee locks up on you.
If it’s floating up around this area, it’s not going to bother you much. But if it’s in the middle of the joint, right around here, it’s going to get stuck, and it’s going to be like walking with your shoes that has a pebble in it and actually will occasionally hurt when you step directly on the pebble, but otherwise it doesn’t bother you much. Same thing with these loose bodies in the joints, so that’s another reason to get evaluated by an orthopedic specialist just to make sure that there’s nothing serious going on in the joint regarding these loose bodies, because they can wear down the cartilage around that area. Every time it bumps up and down against this cartilage, it can speed up arthritis and cause problems.
he last thing you need to be concerned about regarding any kind of locking, or catching or popping sensation in the knee is the knee cap and this is actually very common. The knee cap here tracks in this groove right here. This is called the trochlear groove, and the knee cap goes right down the middle of this groove and it’s usually centralized within that groove. Occasionally patients can have a history of dislocation of the knee cap or can have what’s called maltracking of the knee cap, where the knee cap actually tracks laterally on the outside of that groove, and rubs up and down this condyle here of cartilage.
That can cause pain with stairs, squatting, kneeling any kind of bending activity. If you’re in a movie theater and you go to stand up and you feel a click or a pop and it hurts, that might be the fact that your knee cap was sitting out here laterally, and then it popped back into joint, in the trochlear here and that’s easily addressable with strengthening exercises as well as conservative measures.
Now, if you do have a dislocation of the knee cap, where it pops completely out of joint and you physically have to pop it in or a trainer pops it in. Then that can be a little bit more serious because a ligament injury can occur and there can be some cartilage defects that need to be evaluated by an orthopedic surgeon probably with an MRI and a physical exam. Depending on what the findings are will determine the treatment and sometimes it’s even surgery.
So once again, if you do feel a pop or lock of the knee followed by a pain and diffusion, I highly recommend being evaluated by an orthopedic specialist for further recommendations. I hope this sums up some of the basic answers regarding knee pain and feeling popping in the knee. If you have any further questions, please call my office at 281-633-8600. Thank you very much.
Because the causes of knee pain are varied, you should have an experienced knee specialist evaluate your knee injury. Dr. Bennett has many years of experience successfully treating a variety of knee injuries and knee arthritis so call for an appointment to start on the road to recovery from knee pain and knee stiffness. You don’t want to ignore knee pain or knee popping or locking. If you do, it can make it more likely that treating your knee injury will require a total knee replacement at some point.