What does it mean to have a ruptured ligament? Is it possible for it to stick out and look like a bone?
Having a ruptured ligament means that a part of the connective tissue holding a joint together is broken. Ligaments are not hard like bone and so wouldn't stick out like bone.
Imagine what the insides of your knee look like. What you have is the thigh bone (femur) above, the shin bone (tibia) below (there is also the knee cap (patella) but let's ignore that for the moment). The two need to move like a hinge with each other. But how do they stay connected? That is the job of ligaments - short pieces of connective tissue that connect bone to bone to keep them together. The job does not belong to muscles - they are there to move the bones relative to each other so that there is movement in the joint.
When a ligament ruptures, it means that a part of the support system for that particular joint is broken. This results in a lot of pain, swelling, bruising, and the like. However, it isn't a solid hard material, like bone, and so won't stick out like bone.
Most of the searches I found for a physical representation of a ruptured ligament show orthopaedic surgeries, but I think this photo shows a good example of what you'd see on the skin from a ruptured ligament: