The most common symptoms of a meniscus tear are pain along the side of the knee joint, swelling, and a catching or locking sensation when you try to bend or straighten your leg. These symptoms don’t always appear right away. With smaller tears, it can take 24 hours or more before pain and swelling set in, which is why many people initially assume they just tweaked their knee.
The Core Symptoms
A torn meniscus typically produces a recognizable cluster of symptoms in and around the knee:
- Pain when twisting or rotating the knee. The pain is usually sharp and localized to one side of the joint, felt most intensely when you pivot, turn, or bear weight on the affected leg.
- Swelling and stiffness. The knee gradually puffs up as fluid accumulates inside the joint. This swelling can make the knee feel tight and hard to bend.
- A popping sensation. Many people feel or hear a pop at the moment of injury, though this doesn’t happen with every tear.
- Difficulty fully straightening the knee. The torn tissue can physically block the joint from reaching full extension.
- Locking. The knee gets stuck in one position because a loose fragment of cartilage has wedged itself between the bones of the joint.
- Giving way or buckling. The leg feels weak or unstable, as if the knee might collapse under you.
That buckling sensation isn’t just about structural damage. When a piece of torn meniscus shifts out of place and the joint swells, it disrupts the feedback loop between your knee and the muscles in your thigh that stabilize it. Your leg genuinely responds more slowly, which creates that unsettling feeling of weakness.
Why Symptoms Are Often Delayed
Unlike a ligament tear, which tends to produce immediate, dramatic swelling, a meniscus tear often starts out feeling manageable. You might finish a game or walk home before realizing something is wrong. Small tears in particular can take a full day or longer before noticeable pain and swelling develop. This delay happens because the meniscus has limited blood supply in its inner portion, so the inflammatory response builds more gradually than it would with a well-vascularized tissue.
Some people continue walking and even exercising on a torn meniscus for weeks, noticing only intermittent pain during certain movements. The tear doesn’t heal on its own during this time, and repeated stress can make it worse.
What Locking and Catching Feel Like
Locking is the most distinctive symptom of a meniscus tear because few other knee injuries produce it. It happens when a torn flap or fragment of cartilage folds into the center of the joint, physically blocking the bones from gliding past each other. The fragment gets pinched between the top of the shinbone and the bottom of the thighbone, and the knee simply won’t move further in that direction.
A truly locked knee will neither fully bend nor fully straighten. This is different from stiffness caused by swelling, where the knee resists movement but you can push through it. A locked knee has a hard mechanical stop. Sometimes the fragment shifts back into place on its own after a few seconds or minutes, and the knee suddenly moves freely again. Other times the knee stays locked and requires medical attention.
Catching is the milder version: a brief snag or click during movement, as though something inside the knee momentarily gets in the way before releasing. You’ll notice it most during deep bending, like squatting, or when going up and down stairs.
Traumatic Tears vs. Degenerative Tears
The way symptoms show up depends heavily on how the tear happened. In younger, active people, a meniscus tear is usually traumatic. It occurs during a forceful twist, a sudden stop, or an awkward pivot. There’s often a clear moment of injury, sometimes with an audible pop, followed by progressive swelling over the next day or two. The pain is sharp and easy to pinpoint.
In adults over 40, meniscus tears are more often degenerative. The cartilage has worn down over years of use and can tear with surprisingly little force. Kneeling, deep squatting, or even just standing up from a chair can be enough. These tears tend to come on gradually rather than in a single dramatic moment. The pain may start as a vague ache that worsens over weeks, and you might not remember a specific injury. Swelling tends to be mild and intermittent rather than sudden.
Degenerative tears are also harder to distinguish from osteoarthritis, since both conditions are common in the same age group and often coexist. A useful distinction: meniscus tears tend to produce sharp, localized pain with mechanical symptoms like catching or clicking, while arthritis causes a duller, more diffuse ache with general stiffness that improves as you warm up.
Stairs, Squatting, and Everyday Triggers
Certain activities reliably make meniscus symptoms worse. Walking up or down stairs is one of the most commonly reported triggers, because each step forces the knee to bear your full body weight through a range of motion that loads the meniscus. Squatting is another consistent aggravator, compressing the torn cartilage at the deepest point of knee flexion. Twisting motions, like turning to reach something while your foot stays planted, can reproduce the sharp pain even during routine daily tasks.
Many people find that their knee swells noticeably after these activities, even if it felt relatively normal at rest. The pattern of symptom-free rest followed by flare-ups during specific movements is characteristic of a meniscus tear.
How a Meniscus Tear Is Diagnosed
A physical exam is usually the first step. Your doctor will press along the joint line of your knee to check for tenderness, then perform specific maneuvers designed to stress the meniscus. The most well-known is the McMurray test, where the knee is bent and rotated while the examiner feels for a click or catches along the joint line. This test picks up about 80 to 91 percent of meniscus tears, depending on how soon after the injury it’s performed. Another test, the Thessaly test, involves standing on one leg with the knee slightly bent and rotating your body. It has a diagnostic accuracy of 94 to 96 percent.
An MRI is the gold standard for confirming the tear and determining its size, shape, and exact location. This information matters because it determines whether the tear is likely to heal on its own, respond to physical therapy, or require surgical repair.
When a Locked Knee Needs Urgent Care
Most meniscus tears can be evaluated at a regular appointment, but a knee that locks and stays locked is a different situation. A persistently locked knee means a displaced fragment is trapped inside the joint, and it typically needs prompt intervention to prevent damage to the smooth cartilage surfaces that allow the bones to glide against each other. If your knee locks repeatedly or won’t unlock at all, that’s a signal to seek care soon rather than wait it out.
A meniscus tear that causes frequent catching, chronic swelling, or recurrent locking should also be addressed before it causes secondary damage, even if the symptoms feel manageable between flare-ups. The torn fragment can grind against the joint surfaces over time, accelerating wear that wouldn’t otherwise occur.