You have various ligaments throughout your body. At every joint, there are ligaments holding the bones together and offering support and stability. In a way, these structures are very similar to tendons.
Certain ligaments help with movement, while other ligaments prevent movements from happening. When a ligament is sprained, it creates laxity. This may create instability at the joint, which is why exercise and strengthening are an important part in any rehabilitation program. Strong muscles support the joint and provide the stability it may lack after a ligament injury.
In particular, one of the most injured ligaments in the human body is the anterior cruciate ligament (ACL). This ligament is important for the stability of the knee joint. If torn, surgery must be done to repair it. Sometimes, this involves replacing the ligament with an artificial piece.