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The meniscus has a long and interesting history in orthopedic surgery.
Early surgeons recognized that injuries inside the knee could cause pain, swelling, catching, and disability long before we had the imaging tools that we use today. Surgeons such as Thomas Annandale, McMurray, and Fairbank helped shape our early understanding of meniscus injuries and their consequences.
Fairbank, in particular, described the changes that can occur in the knee after the meniscus is removed. That was an important observation, because it helped surgeons understand that the meniscus was not simply a useless piece of cartilage. It had a purpose.
For many years, diagnosing a meniscus tear was difficult. Physicians relied on the patient’s symptoms and physical exam findings. Later, they adopted imaging studies such as arthrography. One of the more fascinating chapters in that history was the air arthrogram, where air was injected into the knee to outline the joint.
By modern standards, that sounds primitive. In some cases, it was also dangerous. There were reports of serious complications, including deaths from air embolism, before techniques improved and safer imaging methods became available.
Eventually, diagnostic arthroscopy and MRI changed everything. Surgeons could finally see the meniscus directly. MRI allowed us to identify tears, blood supply, root injuries, and associated ligament injuries before surgery.
Today, we understand the meniscus as an important structure with a very specific job.
The Meniscus Is Not Just a Cushion
The knee has two menisci: the medial meniscus on the inside of the knee, and the lateral meniscus on the outside. They are sometimes called the semilunar cartilages because of their crescent-like shape.
The medial meniscus is more open and C-shaped. The lateral meniscus is more circular and more mobile. These differences matter because the two menisci move differently, function differently, and are injured in different ways.
The meniscus is often described as a cushion, but that is a little too simple. It is better thought of as a load-sharing structure.
When the rounded end of the femur pushes down on the relatively flat tibia, the meniscus helps spread that force over a larger area. Its wedge shape and collagen fibers allow it to resist being pushed outward. This is called hoop stress.
In other words, the meniscus takes a downward force and converts part of that force into tension around the ring of the meniscus. That helps decrease pressure on the cartilage surfaces of the knee.
The meniscus also contributes to stability.
In some ways, it acts like a chock block behind a tire. It helps limit abnormal motion of the femur on the tibia, especially when there are ligament injuries. This is one reason meniscus tears are commonly seen with ACL injuries and other rotational injuries of the knee.
Not All Meniscus Tears Are the Same
Some tears are small and located in areas with poor blood supply. These may not heal well. If they are causing mechanical symptoms, they may be treated by trimming the unstable portion. This is called a partial meniscectomy.
The goal is not to remove the whole meniscus. The goal is to remove the unstable torn edge, smooth the remaining tissue, and keep the tear from propagating.
Other tears are more repairable.
Tears near the outer edge of the meniscus are closer to the blood supply. These are often described as being in the red-red or red-white zone. Because these areas have better biology, they have a better chance of healing after repair.
Tears can also be described by their pattern.
A horizontal tear runs parallel to the tibial plateau. A vertical tear runs more perpendicular to it. Radial tears cut across the fibers of the meniscus. These can be more destructive because they interrupt the ring-like function of the meniscus.
Complex tears often have multiple components. These are more commonly seen in degenerative knees, where the tissue has worn and broken down over time.
Root Tears
Root tears deserve special attention.
The meniscus works like a ring, and the roots are the anchors that attach that ring to bone. If the root tears off, the meniscus can lose much of its ability to function.
A root tear can behave almost like a complete loss of the meniscus, because the hoop stress mechanism no longer works normally. Over time, this can lead to increased contact pressure and arthritis-like changes in the knee.
Meniscus Tears and ACL Injuries
Meniscus injuries are commonly associated with ligament injuries.
In an ACL injury, the knee may experience a pivot-shift mechanism, where the femur and tibia rotate and translate abnormally. This can injure the posterior attachments of the medial meniscus, creating what is called a ramp lesion.
On the lateral side, the same injury mechanism can produce tears such as lateral oblique radial tears. These can be difficult injuries, especially in high-level athletes, because the lateral meniscus plays an important role in protecting the outside compartment of the knee.
Degenerative Meniscus Tears
Some meniscus problems are not traumatic.
Many patients develop degenerative meniscus tears over time. These tears may be related to repetitive loading, age-related tissue changes, arthritis, limb alignment, or gradual breakdown of the tissue.
On MRI, these tears can look complex and irregular. During arthroscopy, the meniscus may look frayed, softened, and worn.
This distinction is important because degenerative meniscus tears do not always behave like acute athletic tears.
Several major studies, including trials commonly referred to as FIDELITY, METEOR, and ESCAPE, have shown that many degenerative meniscus tears, especially in middle-aged or older patients with early arthritis or long-standing symptoms, can do just as well with non-operative treatment as with arthroscopic surgery.
Those studies were important, and they changed practice patterns for the better.
Unfortunately, a lot of information online has taken those findings much further than the studies themselves ever intended.
It is now common to see blanket statements that meniscus surgery does not work, or that all meniscus tears should be treated without surgery. That is not what those studies showed.
They primarily examined specific groups of patients with degenerative tears, often in the setting of early arthritis. They did not prove that every meniscus tear in every patient should be treated with physical therapy alone.
The Modern Studies Did Not Erase the History of Meniscus Surgery
That distinction matters because meniscus surgery has a long and successful history for a reason.
When a patient has pain that is truly coming from an unstable meniscus tear, and the tear pattern is appropriate for treatment, the effect of surgery can be very noticeable.
Many patients who have a symptomatic unstable tear treated with a partial meniscectomy feel significantly better afterward. The catching improves. The sharp mechanical pain improves. The knee often feels smoother and more functional.
That clinical effect is part of why partial meniscectomy became such a well-established procedure in the first place. It was not adopted because surgeons misunderstood the meniscus. It was adopted because, in the right patient, it worked.
The modern studies did not erase that history. They refined it.
They helped us understand that degenerative meniscus tears in arthritic or aging knees are different from unstable mechanical tears, displaced tears, traumatic tears, root tears, and tears associated with ligament injuries.
They chipped away at the edges of overuse, especially in patients whose pain may be coming more from arthritis and global knee degeneration than from the meniscus itself.
That is a very different message than saying meniscus surgery does not work.
A better way to understand the modern evidence is this: partial meniscectomy can be a very effective operation when the meniscus tear is truly the pain generator and the tear pattern matches the patient’s symptoms. It is less reliable when the MRI shows a degenerative tear, but the real problem is arthritis, inflammation, weakness, alignment, or generalized wear in the knee.
This is where patients need to be careful about where they get their information.
A young athlete with a traumatic tear is different from an older patient with a degenerative tear. A locked knee with a displaced bucket-handle tear is different from an MRI finding in a knee that aches with stairs and squatting. A root tear is different from a small frayed edge.
The meniscus tear is only one part of the story.
That does not mean meniscus surgery is always helpful. It means the decision has to match the tear, the knee, and the patient.
Trim It or Repair It
When surgery is considered, there are usually two broad options: trim it or repair it.
A partial meniscectomy removes the unstable torn portion of the meniscus. The advantages are that recovery is usually faster, weight bearing is often allowed early, and the rehab is generally simpler.
For certain tear patterns, especially small unstable tears in areas with poor blood supply, this can be a very reasonable option.
A meniscus repair tries to preserve and heal the torn tissue. The advantage is that preserving meniscus tissue may better protect the knee over the long term.
The tradeoff is that recovery is slower. Patients may need crutches, limited weight bearing, range-of-motion restrictions, more therapy, and a longer delay before returning to work or sport. Repairs can also fail and sometimes require another surgery.
This is where the conversation becomes very practical.
“Save the meniscus” is a good principle, but it has to be applied intelligently. A repair may be best for the long-term health of the knee when the tear pattern and biology are favorable.
A partial meniscectomy may be more appropriate when the tear is not repairable, when the tissue quality is poor, or when the patient’s goals and timeline make repair less favorable.
Biology and Healing
There are also biologic strategies used to improve healing.
These may include techniques that bring blood or marrow elements into the area, or adjuncts such as PRP, bone marrow aspirate, scaffolds, or other biologic materials.
The basic concept is that implants and sutures can hold tissue in position, but the body still has to heal the repair. Healing requires biology.
This is one reason meniscus repairs done at the same time as ACL reconstruction often heal well. Drilling bone tunnels during ACL surgery may bring additional biologic healing factors into the knee.
Discoid Meniscus
There are also anatomic variants, such as a discoid meniscus.
A discoid meniscus is an abnormally enlarged or disk-shaped meniscus, most often on the lateral side. Some people have one without symptoms. Others develop pain, popping, catching, or tearing.
When it becomes symptomatic, treatment may involve reshaping the meniscus into a more normal contour. This is called saucerization. If there is an unstable tear, that tear may also be repaired if possible.
Matching the Treatment to the Knee
The history of the meniscus shows how much orthopedic thinking has changed. It was once treated as a structure that could simply be removed. We now understand that the meniscus is a critical load-sharing and stabilizing structure. We also understand that not every meniscus tear needs surgery, and not every tear should be treated the same way.
The right treatment depends on the patient, the tear pattern, the blood supply, the condition of the cartilage, the presence of ligament injuries, the symptoms, and the patient’s goals.
For some patients, the best treatment is physical therapy and time.
For others, it is a partial meniscectomy to remove an unstable fragment.
For others, it is a repair to preserve the meniscus and protect the knee long term.
The most important part is matching the treatment to the knee in front of us.
