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Torn ACL

What everyone should know about ACL surgery

Choosing the right treatment option for an ACL tear up-front can have lifelong implications. On behalf of Hospital for Special surgery, the world's largest academic medical center specializing in musculoskeletal health, the surgeon members of the HSS Sports Medicine Institute have drafted guidelines for people who are considering ACL treatment. Read the guidelines here.


What is the ACL?

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.

How do you tear your ACL?

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.

deep dive knee - torn acl
View an interactive diagram of a torn ACL and anatomy of the knee

What happens when the ACL is torn?

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.

What should I do if I think I have torn my ACL?

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.

How is a torn ACL diagnosed?

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.

When is ACL surgery recommended?

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.

ACL reconstruction surgical procedure

Reconstruction of the ACL follows a number of basic steps, although they may vary slightly from case to case:

  • The surgeon makes small incisions around your knee joint, creating portals of entry for the arthroscope and surgical instruments.
  • The arthroscope is inserted into your knee and delivers saline solution to expand the space around the joint. This makes room for surgical tools, including the arthroscopic camera, which sends video to a monitor so that your surgeon can see inside your knee joint.
  • Your surgeon evaluates structures that surround your torn ACL, including the meniscal cartilage and the articular cartilage. If either of these soft tissues have any lesions as a result of your injury, your surgeon repairs them.
  • Next comes the grafting harvest (unless donor tissue will be used, instead of your own). A section of tendon from another part of your body is cut to create a graft, which is then attached at each end to plugs of bone taken from your patella and tibia. These plugs help to anchor the graft that will become your new ACL.
  • Your surgeon inserts your new ACL into your femur and tibia using a flexible guide wire.
  • Screws are used to secure the plugs of bone. Over time, these plugs will be incorporate into the surrounding bone.
  • The surgical instruments are removed to complete the procedure.

Torn ACL reconstruction surgery animation video

Below, view an animation for a more detailed description of a minimally invasive ACL reconstruction.

What is the recovery time for ACL surgery?

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:

  • Strengthening and range-of-motion exercises are started early in the recovery period.
  • Running exercises begin at about four months.
  • Pivoting exercises are started around five months.
  • Return to playing your chosen sports can likely begin at about six months.

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.

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