Observations on Acute Meniscus Tears
In young people, meniscus tears are most likely to be acute, and often they are isolated—without significant damage to ligaments.
One type is a discoid lateral meniscus tear. In most people, the meniscus is crescent-shaped. But a certain percentage of the population has a D-shaped or a discoid lateral meniscus. I believe that the discoid lateral meniscus is a next step in human evolution because it is bigger and distributed more along the joint surface. But because it tends to be an incomplete mutation, some of the tissue is not durable enough and tends to tear.
Many discoid lateral meniscus tears can occur even without a significant fulcrum or twisting. Sometimes there is no apparent mechanism. You go back and try to figure out what happened, and the answer is that nothing really happened. The discoid meniscus, which resembles an elephant ear, just tore and became unstable.
Then you get into meniscus tears that occur from injury, usually from a twisting mechanism. Many times the meniscus will slip out, and the result is a bucket-handle tear. Usually those are pretty large C-shaped meniscus tears close to the periphery of the meniscus. This bucket handle gets caught in the intercondylar notch, and the knee can't fully straighten.
This injury occurs fairly regularly in kids anywhere from 10 to 18 years old. It usually happens during sports. But it could be from falls. It could just be from horsing around, body surfing, or stepping in a hole. It could be a running back who twisted his leg as he stepped in the mud or a basketball player who came down on someone's foot.
The MRI also tells me whether there is a meniscus tear associated with other ligamentous injuries. If the anterior cruciate ligament (ACL) is torn, the risk for damage to the meniscus increases. In fact, patients whose ruptured ACLs have been treated conservatively have a 4.7 times greater incidence of meniscus tears.
Acute meniscus tears can occur through contact or noncontact mechanisms, but both medial and lateral tears seem to be associated especially with noncontact injuries. In the winter, for example, we see a lot of skiing injuries. Ligament injuries are often associated with meniscus injuries.
Degenerative Meniscus Tears in Older Patients
There are very few meniscus injuries that occur from overuse. Overuse more often causes articular cartilage injuries. But menisci do degenerate with time in a kind of natural pathogenesis. Because their blood supply is limited, they often cannot regenerate. The components separate. Then the menisci displace. And when they displace, they cause symptoms.
The articular cartilage may degenerate in these people at the same time. The degeneration of the articular cartilage stimulates a cascade of cytokines, interleukin, and other inflammatory agents that also damage the meniscus. So when people have severe arthritis, their menisci almost always tear. I don't manage these cases operatively because the prognosis is not good.
But I'm starting to treat older patients. I recently replaced the meniscus in a 50-year-old man who was very athletic. He didn't have any degenerative changes, and the bucket-handle tear could not be repaired. Because some people can live to be 100, and we know what happens if you don't have a meniscus, why not put one in there?
Orthobiologics for Patients With Moderate Arthritis
When people have moderate arthritis, I may still operate. But in these cases, I use orthobiologics—such as glucosamine, hyaluronic acid, platelet-rich plasma, and stem cell technology—to help manage it. Arthroscopic surgery alone may not be robust enough.
I use these orthobiologics in many other patients as well. The meniscus only has blood supply in its outer third. So we divide meniscus tears into those with a blood supply, which we refer to as "red-red," those with a limited blood supply ("red-white"), and those with no blood supply ("white-white").
The more "white" the tear, the more important it is to supplement the blood supply with orthobiologics. In the past, surgeons have tried a number of techniques—from clots to platelet-rich plasma, hyaluronic acid, and fenestrations in the meniscus itself.
I'm not aware of any randomized controlled trials testing these approaches. Some recent case-controlled studies of platelet-rich plasma showed mixed results,[7,8] but we know that it, as well as hyaluronic acid, create a more anabolic and healing environment. So I think it's worth using them in some patients.
I usually make those decisions based on the situation. For example, if I'm treating a big tear in a professional athlete—such as an elite basketball, football, or soccer player—I often need that meniscus to heal as quickly as possible and be as durable as possible. So I add platelet-rich plasma and/or hyaluronic acid.
I know that a lot of my colleagues who practice sports medicine on high school, club, and college elite athletes will also use a variety of orthobiologic agents in their patients.
We have gotten better in our technology of repairing meniscus tears. In particular, we can now use specialized devices to repair the meniscus in what we call an "all-inside" approach. The most important concept is to preserve, repair, and restore as much of the meniscus as we can.
These innovations, along with orthobiologics, mean that more and more patients with meniscus tears can benefit from treatment.
Medscape Orthopedics © 2016 WebMD, LLC
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Current Thinking in Surgical Approaches to Meniscus Repair - Medscape - Apr 22, 2016.