Knee locking is an inability to either straighten or bend knee. There are two types of locked knees. The locked knee can either be caused by a block to knee motion, or a locked knee can be caused by pain that is a result of some injury which doesn’t allow knee motion.
When a Knee locking is caused by a mechanical block to motion of the knee, there are most of the times something that is physically being caught within the structure of the knee as a result of which there is a reduced knee motion, in other words the knee is locked.
Patients can also have a locked knee when they have severe pain with any knee motion. Often the cause of a locked knee in this situation is meniscuses tear which is the most common in all knee problems. When this type of meniscus tear occurs, a large fragment of the torn meniscus can become wedged within the knee, preventing normal movement of that knee. It’s always difficult for the patients to determine whether the knee locking is due to some block or knee pain, so a good physical examination can usually find the cause of the locking.