The meniscus is a tough, rubbery piece of cartilage that sits between your thighbone and shinbone, acting as a cushion and stabilizer inside your knee joint. You actually have two in each knee: a medial meniscus on the inner side and a lateral meniscus on the outer side. Together, they absorb shock, distribute your body weight evenly across the joint, and help keep the knee stable during movement.
Shape, Size, and What It’s Made Of
Each meniscus is a crescent-shaped wedge of fibrocartilage, a tissue that’s denser and more flexible than regular cartilage. It’s composed primarily of water (65 to 70 percent) and collagen (20 to 25 percent), with smaller amounts of other proteins that give it a unique ability to compress under load and spring back into shape.
The two menisci aren’t identical. The lateral meniscus, on the outside of the knee, is more tightly curved into a C-shape and covers 75 to 93 percent of the bony surface beneath it. The medial meniscus is wider and more semicircular, covering only 51 to 74 percent of the inner surface. Both are anchored at their front and back ends to the top of the shinbone. This difference in size and coverage helps explain why the medial meniscus is more commonly injured: it’s less mobile and absorbs more force during twisting movements.
What the Meniscus Actually Does
The meniscus does far more than pad the joint. On the inner side of the knee, the medial meniscus carries roughly 61 percent of the total load, leaving only 39 percent for the cartilage covering the bone itself. During activities like pushing off while walking, that share can climb to 78 percent. Without this load-sharing, the cartilage on your bones takes a beating. Studies using biomechanical models show that removing the medial meniscus entirely increases the force on the underlying cartilage by about 179 percent, nearly tripling the stress on surfaces that weren’t designed to handle it alone.
Beyond load distribution, the menisci deepen the shallow surface of the shinbone, creating a more stable cradle for the rounded end of the thighbone. They also help lubricate the joint and contribute to proprioception, your knee’s internal sense of where it is in space.
Why Blood Supply Determines Healing
One of the most important things about the meniscus is that not all of it can heal equally. Blood supply reaches only the outer third, known as the “red-red zone.” The middle third, the “red-white zone,” has partial blood flow. The inner third, the “white-white zone,” has no blood supply at all and relies on joint fluid for nutrition.
This matters because tissue needs blood to repair itself. Tears in the outer, vascularized zone heal relatively well, especially with surgical repair. Tears in the inner avascular zone often can’t heal on their own and may need to be trimmed away rather than stitched. The location of a tear is one of the first things a surgeon evaluates when deciding how to treat it.
How Meniscus Tears Happen
Meniscus tears fall into two broad categories: traumatic and degenerative. Traumatic tears typically happen in younger, active people during a sudden twist or pivot, often while the foot is planted and the knee is bent. Sports with frequent cutting and contact carry higher risk. Among college athletes, wrestling and rugby show the highest rates of isolated meniscus tears.
Degenerative tears are different. They develop gradually as the meniscus weakens with age, and they can occur during ordinary activities like squatting or stepping off a curb. These tears are considered part of the broader process of knee osteoarthritis rather than a standalone injury.
The tear itself can take several forms. A horizontal tear splits the meniscus into upper and lower layers. A longitudinal tear runs along the length of the meniscus, and when it’s large enough to flip into the center of the joint, it’s called a bucket-handle tear. Radial tears cut across the fibers perpendicular to the meniscus’s main curve. Oblique tears, sometimes called parrot-beak tears, run at an angle. Complex tears combine two or more patterns and are generally harder to repair.
Symptoms of a Torn Meniscus
The hallmark symptoms include pain along the joint line (the seam where your thighbone meets your shinbone), swelling, and stiffness. Many people report a popping sensation at the moment of injury. Twisting or rotating the knee tends to make the pain worse.
Two symptoms are particularly telling. Mechanical locking occurs when a displaced piece of torn meniscus physically blocks the knee from straightening fully. It’s different from stiffness: the joint literally gets stuck in a bent position. The other is a giving-way sensation, where the knee feels unstable and buckles unexpectedly. Not every tear causes locking or giving way, but when these symptoms are present, they strongly suggest a meniscus problem that may not resolve on its own.
How a Tear Is Diagnosed
Doctors use a combination of physical examination and imaging. Two common in-office tests help identify a torn meniscus before ordering a scan. In the McMurray test, you lie on your back while the provider bends and rotates your knee, feeling for clicks or pain. The Thessaly test is done standing: you balance on one leg with a slight knee bend, then twist your knee inward and outward three times while the provider holds your arms for support. Pain or a catching sensation during either test suggests a tear. MRI is typically used to confirm the diagnosis and determine the tear’s type, size, and location.
Treatment: When Surgery Is and Isn’t Needed
The treatment approach depends almost entirely on whether the tear is degenerative or traumatic. These are treated as fundamentally different problems.
Degenerative Tears
Degenerative tears are generally treated without surgery. The first-line approach includes modifying activity to reduce knee stress, weight management, anti-inflammatory medication, and a structured physical therapy program. Exercise therapy typically involves two to three sessions per week of progressive strengthening and neuromuscular training. If there’s no meaningful improvement after 12 weeks, referral to an orthopedic surgeon may be warranted, but surgical removal of the damaged tissue is reserved for rare cases where conservative treatment has clearly failed.
Traumatic Tears
Traumatic tears, especially in younger patients, are more likely to need surgery. The goal is to preserve as much meniscus as possible. Tears in the vascularized outer zone are often repairable with sutures during an arthroscopic procedure. Vertical longitudinal tears in the red-red or red-white zone tend to have good outcomes after repair, with high rates of patient satisfaction. When a tear is in the avascular inner zone or too damaged to stitch, the torn portion is trimmed away in a procedure called partial meniscectomy.
Recovery After Surgery
Recovery timelines differ significantly depending on the procedure. After a partial meniscectomy, where damaged tissue is simply removed, recovery is faster because there’s no repaired tissue that needs to knit back together.
Meniscus repair takes longer. You’ll need crutches for at least a few weeks to keep weight off the knee while the stitched tissue heals inside the joint, a process that can take up to three months. Physical therapy continues for several months after surgery. Once you can walk without crutches, expect a few more weeks before light activities feel comfortable. Clearance for intense physical activity or sports may take several months beyond that.
Long-Term Impact on Knee Health
Preserving meniscus tissue matters for the long-term health of your knee. In a study of patients with traumatic tears (average age around 30), 17 percent of those who had a partial meniscectomy eventually developed symptomatic knee osteoarthritis, compared to 10 percent of those who had a meniscus repair and just 2.3 percent in the general population. After accounting for age and sex, patients who had their meniscus repaired rather than partially removed had roughly half the rate of developing osteoarthritis over the follow-up period.
This is why surgeons increasingly prioritize repair over removal when the tear location and pattern allow it. Every bit of meniscus that remains intact continues to share load, protect cartilage, and delay the wear-and-tear process that leads to arthritis down the line.