ACL or Anterior Cruciate Ligament in medical terms is soft bone located in the middle of the knee between the femur (thigh bone) and tibia (shin bone).  It keeps the two bones together and preventing to slide towards the skin.   Accidents may render a person with ACL injury.  In some cases the damage to the ligament is not noticeable or someone is not aware that the ligament was already damaged.  How can a person know that their ligament was damaged? There are symptoms that can help you determine the problem, a sudden popping sound in the knee during injury, a swell in the knee that appears after 6 hours from injury and most especially a striking pain when you try to move of bend your knee.  The main causes of ACL tears is mainly a contact and non-contact injury or a strong blow at the side of the knee which can be acquired during a football tackle for example.  Some may caused by sudden shift of direction at a full stop while running, landing from a jump, pivoting and over stretching the knee.

Adults are more likely to tear their ACL but women is more susceptible to it, it's just not so clear as to why it is but possibly due to difference of anatomical structure of a male from a female.  People who tear their ACL mostly in adults is most likely to pull off their ACL and unfortunately this injury won't heal by themselves. Kids have a tendency to sustain the same injury as well but evidently the femur still has the ligaments on it and eventually would heal overtime.  If in case the ACL tear didn't heal a surgical operation is needed to fix the bone.  If there is an evidence of ACL injury symptoms, MRI test will help prove the diagnosis.  Some people can withstand having a torn ACL and still able to function normally. However, they may complain about constant pain in the knee and may feel like it's about to give out, person who has a torn ACL and left unrepaired is also prone to early signs of arthritis in the affected knee. 

 If an injury happens it must be treated with first aid, elevate the joint (above the level of the heart), putting in ice compress or just simply put ice on top of the injured area and most of all taking in a nonsteroidal anti-inflammatory medication like ibuprofen.   In the event of any inflicted serious knee injury, never to move the joints for it will just make the pain more intense.  Seek immediate help from a professional for evaluation and X-ray test.  This will help them identify the severity of the ACL tear and to be able to apply appropriate remedy.