A torn cartilage in the knee (meniscus) usually hurts especially when you twist or rotate your knee. You may also feel a popping sensation as if a bubble burst inside the skin from within your knee/knees. Swelling may also occur. In a more severe injury, locking can also be felt wherein a person could not completely extend their legs as it feels like it is sealed in a certain position.
Torn cartilage in the knee is also called a torn meniscus. When this injury occurs the symptoms include pain and swelling of the knee, tenderness the meniscus is pressed, a popping or clicking in the knee and limited motion of the knee joint.