The meniscus is a C-shaped wedge of tough, rubbery cartilage that sits between your thighbone and shinbone, acting as a cushion and stabilizer inside the knee joint. You actually have two in each knee: the medial meniscus on the inner side and the lateral meniscus on the outer side. Together, they absorb shock, distribute your body weight evenly across the joint, and help the knee move smoothly through its full range of motion.
What the Meniscus Is Made Of
Both menisci are made of fibrocartilage, a tissue that’s tougher and more flexible than the smooth cartilage capping the ends of your bones. Think of it as a firm rubber gasket: stiff enough to bear heavy loads but pliable enough to change shape slightly as your knee bends and twists. Each meniscus is wedge-shaped in cross-section, thicker at the outer rim and tapering to a thin edge toward the center of the joint. That wedge shape helps the rounded end of the thighbone sit snugly on the flatter surface of the shinbone.
How the Meniscus Protects Your Knee
Without menisci, the full force of every step would concentrate on a small point of contact between two bones. The menisci spread that load across a much wider area of the shinbone, reducing stress on the joint surface. They also act as shock absorbers during impact activities like running, jumping, and going downstairs.
Beyond cushioning, the menisci improve joint stability by deepening the shallow surface of the shinbone so the thighbone doesn’t slide around as easily. They even play a role in proprioception, your body’s sense of where your knee is in space. Nerve fibers and specialized receptors in the outer portion of each meniscus send signals to your brain about joint position and movement, helping you balance and adjust your stride without consciously thinking about it.
Blood Supply and Why It Matters for Healing
One of the most important things to understand about the meniscus is that not all of it can heal equally. Blood vessels and nerves penetrate only the outer portion, reaching roughly the middle third at most. The innermost portion has no blood supply at all. Surgeons divide the meniscus into three zones based on this:
- Red zone: the outer third, which has good blood flow and the best healing potential.
- Red-white zone: the middle third, with limited blood supply and moderate healing ability.
- White zone: the inner third, which is avascular and heals poorly on its own.
This is why the location of a tear matters so much. A tear in the red zone can often be repaired surgically and expected to heal, while a tear in the white zone may not heal even with stitches, because the tissue simply can’t deliver enough blood to mount a repair response.
How Meniscus Tears Happen
Meniscus tears fall into two broad categories: traumatic and degenerative. Traumatic tears tend to happen in younger, active people. A sudden twist or pivot while the foot is planted and the knee is bent, common in sports like soccer, basketball, and skiing, can rip the meniscus. Degenerative tears develop gradually as the fibrocartilage weakens with age and repeated use. Everyday activities like squatting or stepping off a curb can be enough to tear tissue that’s already worn thin.
Degenerative tears are remarkably common. About 28% of middle-aged and older adults have a medial meniscus tear visible on MRI without any symptoms at all. That number climbs steadily with age: roughly 32% of people between 65 and 70, 40% between 70 and 75, 48% between 75 and 80, and over 52% of those past 80. Many people walk around with a torn meniscus and never know it.
What a Torn Meniscus Feels Like
When a tear does cause symptoms, the classic signs include pain along the joint line (the seam where your thighbone meets your shinbone), swelling that builds over several hours, and a sensation that your knee might lock up or give way beneath you. Some people hear or feel a pop at the moment of injury. Bending deeply or twisting the knee usually makes the pain worse, and you may notice your knee catching or clicking during movement.
Not every tear causes dramatic symptoms. Small degenerative tears may produce only mild, intermittent aching that you notice after long walks or when climbing stairs. Larger or displaced tears, where a flap of cartilage folds into the joint, tend to cause more obvious mechanical problems like true locking, where the knee temporarily won’t straighten all the way.
How a Meniscus Tear Is Diagnosed
Doctors typically start with a physical exam involving specific maneuvers designed to stress the meniscus. During the McMurray test, you lie on your back while the examiner bends and rotates your knee, feeling for a click or pain that suggests a tear. The Thessaly test takes a different approach: you stand on one leg with your knee slightly bent and twist your body side to side while the examiner supports your arms. Pain or a catching sensation during either test points toward a meniscus problem.
These clinical tests are useful but not perfect. An MRI is usually ordered to confirm the diagnosis, pinpoint the tear’s location and pattern, and help determine whether the tear is in a zone that can heal. The location within those red, red-white, or white zones directly shapes the treatment plan.
Treatment: Repair vs. Removal
Small, stable tears in the outer (red zone) portion sometimes heal with rest, ice, and physical therapy alone. When surgery is needed, the two main options are meniscus repair, where the torn edges are stitched back together, and partial meniscectomy, where the damaged portion is trimmed away.
The long-term difference between these two approaches is significant. A comparative study following patients for more than 10 years found that those who had a meniscus repair scored substantially higher on every measure of knee function, including pain, daily activities, and sports participation, compared to those who had the damaged tissue removed. Perhaps more importantly, only two of the ten repair patients developed even mild early arthritis on X-ray. In the meniscectomy group, most patients showed moderate to severe arthritic changes by the 10-year mark. Preserving the meniscus protects the joint surface over time because the remaining tissue continues doing its job of spreading load and absorbing shock.
That said, not every tear is repairable. Tears in the avascular white zone, complex tears with multiple fragments, and severely degenerated tissue often can’t be stitched successfully. In those cases, trimming the damaged portion is the more practical option. Recovery from a meniscectomy is faster, typically a few weeks, while a repaired meniscus requires more protected healing time, often four to six months before full return to activity, because the stitched tissue needs time to knit together with adequate blood supply.
Living With Meniscus Wear
Given how common asymptomatic degenerative tears are, an MRI finding of a meniscus tear doesn’t automatically mean you need surgery. Many people with mild degenerative tears manage well with strengthening exercises that support the knee, activity modifications, and occasional anti-inflammatory relief. Keeping the muscles around the knee strong, particularly the quadriceps and hamstrings, helps compensate for some of the stability and load-sharing the meniscus provides.
If you’ve had part of your meniscus removed, maintaining muscle strength and a healthy body weight becomes even more important. Every pound of body weight translates to several pounds of force across the knee during walking, and with less meniscus tissue to distribute that load, the remaining cartilage surfaces bear the extra burden. Staying active with lower-impact exercise like cycling, swimming, or walking on flat ground helps keep the joint healthy without grinding down what’s left.