With knee injuries, it can be hard to keep track of what exactly each injury entails. With that in mind, here's a short primer on the various types of knee injuries that may occur in MMA.
The main categories of injuries that MMA fighters may experience either involve the ligaments or the menisci. This article will focus on ligamentous injuries. The main ligaments of the knee are the ACL, PCL, MCL and LCL.
ACL AND PCL INJURIES
Ligaments are soft tissue structures that run from one bone to another. This is in contrast to tendons, which are the ends of muscles that thicken and insert into bones to allow them to pull. The knee is composed of the femur (thigh bone), the tibia (shin bone), and patella (knee cap). Within the center of the knee are two ligaments that cross each other (‘cruciate’ = crossing).
The ACL, or anterior cruciate ligament, lies in front (‘anterior’ = front) and the PCL, or posterior cruciate ligament lies in the back (‘posterior’ = back).
The ACL serves two functions. It prevents the tibia from moving forward relative to the femur and also provides rotational stability for sudden direction changes. When it is ruptured, sudden changes in direction can cause the knee to buckle.
For this reason, if an athlete has an ACL rupture, it is usually reconstructed. It cannot heal on its own or be repaired because, due to its location, it cannot form a blood clot that provides a scaffold for healing.
There are several options for grafts for ACL reconstruction. The most common include using the patellar tendon (the tendon running from the knee-cap to the tibia) with bone on the ends of the graft or part of the hamstrings in the back of the knee without bones on the ends of the graft. The other option is to use an ‘allograft’ from a cadaver.
The benefit of using the athlete’s own tissue (‘autograft’) is that it heals stronger. However, there is some pain and weakness associated with harvesting the graft. Once the surgery is performed, the rehabilitation is a long process, usually taking up to a year before an elite athlete returns to competition (see the career of Georges St Pierre).
The PCL is a much more rare injury and is discussed much less, although Mark Hunt had his repaired. The PCL is important in keeping the tibia from moving backwards relative to the femur. Like the ACL, the PCL cannot heal on its own and must be reconstructed with a graft.
MCL AND LCL INJURIES
The medial collateral ligament, or MCL, lies on the inner (medial) aspect of the knee running from the femur to the tibia. It’s prevents bending of the knee towards the inside when the knee is hit from the outside. When the MCL is injured, it is usually sprained, in which some of the fibers stretch or break, but the ligament is not completely ruptured.
This usually heals in a matter of weeks. If, however, the MCL completely ruptures, it is still able to heal itself because it is enclosed in a sheath and can form a clot allowing reparative cells to lay down new tissue.
The lateral collateral ligament, or LCL, lies on the outer side of the knee, connecting the femur to the tibia. It prevents the opposite directed force than the MCL. The LCL is rarely injured in an isolated incident.
Usually, the LCL is injured in a very high-impact injury such as a car accident and involves several other structures on the posterior and lateral side of the knee that can often involve the PCL.
Again, like the MCL, it is more commonly sprained than completely ruptured and can usually heal on its own without surgery. However, if another ligament such as the ACL or PCL is ruptured and requires surgery, it will often be repaired surgically at the same time.
