At last weekend’s UFC 171, what began as a pivotal welterweight title eliminator between Carlos Condit and Tyron Woodley ended with Condit pivoting, collapsing, and grasping his knee in agony and Tyron Woodley emerging as the winner by ever-contentious injury TKO.

Initial reports pointed to possible tears of Condit’s meniscus and anterior cruciate ligament (ACL). With the results of an MRI expected this week, Fightland spoke with Dr. Michael Kelly—a sports-medicine specialist, part-time ringside doctor, and the author of the book Fight Medicine—about the anatomical role of the meniscus, what causes a meniscus tear, its relationship to the ACL, the surgery and recovery, and the road ahead for athletes who have undergone medical procedures on their knees.

Dr. Michael Kelly: The main purpose of the meniscus is to stabilize the knee during flexion. A meniscus is a disc-shaped cartilage—there are two in the knee, the medial and lateral sides. The end of the femur flares out, and there are two contact surfaces on the end of the femur that fit inside each of the meniscus, so that as the femur and tibia articulate, those discs keep it from twisting. When there’s a tear, that’s a literal translation: There’s an actual tear in the cartilage, and it can occur on either the medial or the lateral meniscus, and it can occur anywhere in that circle: the front, the back, the posterior medial side, the posterior lateral side. It can be a simple tear that’s just a straight gash, or it can be a complex tear that goes in different directions. It can be vertical, horizontal, or transverse.

The most common mechanism for a tear in grappling sports, in particular MMA, is when the knee is in a flexed position, and then it’s twisted. Say you’re doing a figure four on the body, or a triangle choke where you’re pulling your ankle toward you. In that position, the tibial plateau—the top of the tibia—and the distal medial side of the femur are pinching the meniscus between the two bones. And as you twist it, it catches and it tears. The majority of the time, if it’s just a simple linear force like that, you’re going to get a simple tear. You start getting into more complex tears when you have forces going in multiple directions, like when someone is trying to defend against that move and they’re exerting force in a different direction—then you have a sudden, abrupt change while the knee is flexed. The lateral side is usually when the knee is hyper-flexed and twisted outwards. If you think of, like in high school wrestling, a basic sit-out move, the way the knee is hyper-flexed, if somebody picks that ankle while it’s hyper-flexed and pulls it up, that can cause tears on the outer meniscus or the lateral meniscus. It’s a similar mechanism, catching it between the two bones and twisting.

The main symptom you’ll see with an acute meniscus tear is pain, obviously swelling that’s interarticular [between the joints], and depending on the location, what we often see is an inability to straighten the knee—the athlete can’t straighten their knee out because the piece of meniscus that got torn gets caught up into the joint and prevents the joint from extending out all the way. In the absence of that, usually what we find are called mechanical symptoms, where you get sharp pain whenever that torn meniscus gets compressed. Patients usually say, “I move a certain way and I get a real bad sharp pain in my knee,” or “I’ll be standing and then when I twist to turn I’ll get a sharp pain.” Fighters in MMA will go to push off on that leg, and if there’s a medial meniscus tear, they might feel it. Or if they pivot on a roundhouse kick, they may feel it on the opposite leg, like a sharp pinching pain.

The standard surgery to repair a meniscus today is done through an arthroscope. Let’s say it’s on the outer edge of a young athlete and it’s fairly new. You go in through a scope and actually suture that cartilage back together, then hopefully it will seal itself down and heal. If a tear is more toward the inner portion of the meniscus, because you don’t have a lot of blood flow there, it’s less likely to heal, so usually you want to cut out the piece that’s causing those symptoms, and again, that’s done through a scope.

When the knee is locked and you can’t extend it, usually that’s an indication for surgery to get the knee to function properly. The other main reason you want to get this repaired, in a younger athlete, there’s some evidence that if the tear is on the outer portion of the meniscus and it’s a young athlete, instead of cutting it out, you can actually repair the meniscus and preserve that cartilage. A failure to do so in a young athlete can result in either a simple tear becoming complex or a small tear becoming worse, and then turning it into a situation where you no longer have the option of repairing it, now you actually have to cut out the torn piece. And whenever you do that, you increase the risk of instability in the knee and more importantly severe arthritis later in life.

The main determinants [in deciding upon surgery] are the symptoms: Are they interfering with the athlete’s ability to perform his chosen endeavor? The other main criterion is how big the tear is. If it’s a little tiny tear that’s on the more anterior part of the knee where it’s not really going to affect the athlete in his daily performance, or cause any of those mechanical symptoms, you may try a conservative approach. The other situation is if it’s an older athlete—a weekend warrior—and there’s a lot of arthritis already in the knee. In that situation, it’s not uncommon to have degenerative tears, where they’re not really causing pain in the knee, they’re just a byproduct associated with that extensive arthritis in the joint.

Once the surgery is completed, the mainstay is physical therapy. Now, there’s evolving evidence, and it’s becoming standard practice now with meniscal repairs, to inject a substance of viscosupplementation. It’s a hyaluronic acid, the natural component of a healthy joint. And there’s some evidence that athletes who have meniscus surgery and then add gel, that lubricant shot injected afterward, recover better. It’s a series of injections. There are newer treatments that are evolving, but the evidence isn’t quite there to say we’re definitively going to do this in all athletes. There’s a lot of research on cartilage regeneration with stem cells and other experimental treatments to try and get that cartilage to heal better.

The ACL and meniscus are actually intimately related biomechanically. The ACL controls the movement of the proximal tibia in relation to the distal femur—it keeps the closest part of the tibia from sliding forward on the femur. If that gets torn with trauma, you suddenly lose the ability to stabilize the knee in a front to back direction, or actually a back to front direction. So if you lose that stability there, and then you’re flexing the knee and twisting it, now you’ve just magnified the force on the meniscus and you’re more likely to get a tear. There’s something in contact sports called the Unhappy Triad, where you get an ACL tear, a medial meniscus tear, and a medial collateral ligament (MCL) tear. And that’s usually related to a blow on the outside of the knee while it’s flexed.

We have a pretty good understanding that eventually there’s going to be some arthritic changes in the knee [of an athlete who has had meniscus surgery]. Osteoarthritis in the knee is defined as a loss of cartilage on the protective surfaces of the bone, resulting in pain, stiffness, and dysfunction. And if you think about it, if you change the biomechanics of the knee, whether it’s from trauma, surgery, or both, you suddenly have different forces affecting those cartilage surfaces of the knee that the body is not necessarily designed to accommodate. So eventually, those increased forces or changing forces will lead to a wearing away of that cartilage and some arthritic damage down the road. It depends on how long after the trauma it occurs, how old the athlete was when they initially had trauma, how extensive the surgery was—did they repair a meniscus or cut out a piece—and did they have other injuries, like an ACL injury or MCL injury or both. But the current treatment pattern today is to try and maximize the sparing of the cartilage of the meniscus and the cartilage on the end of the bone. And I think over the next 10, 20 years, we’re going to see a marked improvement where athletes are having less severe arthritis after these injuries, because of that cartilage-sparing protocol.

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