How do ligaments help joints stay stable?

Ligaments connect one bone to another, unlike tendons, which connect muscle to bone. Their collagen-rich structure gives them strength while still allowing some flexibility at joints such as the knee, ankle, and wrist. By controlling how far a joint can move, ligaments help keep movements smooth and safe. If a ligament is stretched or torn, the joint may become unstable, as in an ankle sprain or knee injury. They are a key part of the body's passive support system.