The anterior cruciate ligament (ACL) is one of four major ligaments in the knee and has a primary role in maintaining knee stability. It is part of the complicated network of tendons and ligaments that help stabilize and support the knee. The ACL is particularly vulnerable to injury during athletic activity or as the result of impact, and a torn ACL is a common injury in athletes of all levels. It is especially common in sports with a lot of planting, cutting, and pivoting, such as soccer, basketball, skiing and football. ACL surgery is often required to repair an ACL tear.
A partial or complete ACL tear (rupture) often occurs with a sudden twisting movement when a person stops quickly and changes direction, especially while pivoting or landing after a jump. A sudden impact to the knee can also result in a torn ACL.
Athletes with an ACL tear often hear or feel a "pop" at the time of injury. The knee will quickly swell, and, in many cases, feel unstable. An ACL tear is often accompanied by other injuries to the knee, such as to cartilage or additional knee ligaments.
Immediately after ACL injury, it is important to decrease the inflammation in your knee by applying ice and taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. You should then consult an orthopedic surgeon or sports medicine physician as soon as possible. Physical therapy will be critical to strengthen the surrounding muscles and improve the range of motion of the knee.
Your doctor can usually diagnose a torn ACL through a physical exam, although an MRI is very helpful and crucial for determining whether there are injuries to other parts of the knee.
Some ACL injuries can be treated with physical therapy alone, and you may be able to lead an active, healthy lifestyle without surgery, depending on the severity of the injury. However, if you are an athlete and you want to continue to perform at a high level or participate in physically demanding activities, ACL reconstruction surgery is often needed.
In most cases, it is not possible to repair or reattach a torn ACL. This is why we refer to surgical "reconstruction." Your surgeon will most likely need to make a completely new ACL for you. Your new ACL will be constructed from a graft of replacement tissue, either from your own hamstring or patellar tendon, or from an allograft (human donor tissue). The reconstruction is performed, using arthroscopic surgery, through several small incisions around the knee.
Reconstruction of the ACL follows a number of basic steps, although they may vary slightly from case to case:
Below, view an animation for a more detailed description of a minimally invasive ACL reconstruction.
You will be able to walk with crutches and a leg brace on the day of surgery. However, it usually takes six months before you will be able to return to participating in sports after an ACL reconstruction, depending on the level of competition and the type of activity.
You will begin physical therapy very soon after surgery, with a progression of exercises:
Arthroscopy has made the recovery period quicker easier, compared to when ACL construction was conducted through open surgery. But to achieve a successful outcome, it is critical that your rehabilitation be carefully supervised by an appropriate physical therapist and follow-up appointments with your surgeon.
Below, explore articles and other content on ACL injuries or select Treating Physicians to find the best doctor or surgeon at HSS to suit your specific condition and insurance.
Read more discussions on ACL injuries.
Read detailed content on treatments for ACL tears.
Learn about performance exercises and other ways to help avoid tearing your ACL.
Read information about related injuries and about the heightened risk of future osteoarthritis of the knee resulting from a torn ACL.