Surgery, if recommended, is generally not performed until the initial inflammation from the injury has resolved.About 200,000 people are affected per year in the United States. In some sports, females have a higher risk of ACL injury, while in others, both sexes are equally affected. While adults with a complete tear have a higher rate of knee osteoarthritis, treatment strategy does not appear to change this risk. ACL tears can also occur in some animals, such as dogs. The most common knee injury in dogs is ACL or CCL rupture; in fact, till proven otherwise, unexpected hind limb lameness is usually due to a ruptured cruciate. Signs and symptoms
When an individual has an ACL injury, they are likely to hear a "pop" in their knee followed by pain and swelling. They may also experience instability in the knee once they resume walking and other activities, as the ligament can no longer stabilize the knee joint and keep the tibia from sliding forward.Reduced range of motion of the knee and tenderness along the joint line are also common signs of an acute ACL injury. The pain and swelling may resolve on its own; however, the knee will remain unstable and returning to sport without treatment may result in further damage to the knee. Causes
Causes may include:

Changing direction rapidly (also known as "cutting")
Landing from a jump awkwardly
Coming to a sudden stop when running
A direct contact or collision to the knee (e.g.
This method is less invasive and is proven to result in less pain from surgery, less time in the hospital, and quicker recovery times than "open" surgery (in which a long incision is made down the front of the knee and the joint is opened and exposed).The timing of ACL reconstruction has been controversial, with some studies showing worse outcomes when surgery is done immediately after injury, and others showing no difference in outcomes when surgery is done immediately compared to when surgery is delayed. The American Academy of Orthopedic Surgeons has stated that there is moderate evidence to support the guideline that ACL reconstruction should occur within five months of injury in order to improve a persons function and protect the knee from further injury; however, additional studies need to be done to determine the best time for surgery and to better understand the effect of timing on clinical outcomes.Young athletes who have early surgical reconstruction are more likely to return to their previous level of athletic ability when compared to those who underwent delayed surgery or nonoperative treatment. They are also less likely to experience instability in their knee if they undergo early surgery. There are over 100,000 ACL reconstruction surgeries per year in the United States. Over 95% of ACL reconstructions are performed in the outpatient setting. The most common procedures performed during ACL reconstruction are partial meniscectomy and chondroplasty.