When to worry about knee locking with a meniscus tear

A meniscus tear can cause pain, swelling, catching, or a mechanical block to movement. A displaced portion may sit between moving joint surfaces, while inflammation can make bending and straightening difficult. A knee that feels stiff but gradually loosens is not the same as one that cannot move through its usual range.

The symptom does not prove the cause. Tell a clinician about the injury mechanism, the exact movement that catches, any pop, and whether the knee is fully straight between episodes.

Stop and sit safely rather than forcing the knee through the block. Avoid pivoting, deep squats, kneeling, running, and repeated self-testing. Support the leg and use a cold pack wrapped in cloth for uncomfortable swelling.

Arrange a prompt examination for recurrent catching or locking, especially if walking, work, or sleep is affected. Rehabilitation and activity changes depend on the examination and how the tear behaves.

Get urgent help if the knee remains locked, is deformed, swells rapidly after injury, or cannot bear weight. A hot red knee with fever, new numbness, or a cold or pale foot needs immediate assessment as well.

Ask whether the locking suggests a mechanically displaced tear, whether imaging is needed, what movements to avoid, and how to preserve strength safely. Mention any fall, instability, swelling, and inability to straighten the knee.