Anterior Cruciate Ligament (ACL) Injuries

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. ACL tears occur in athletes of all levels. It is extremely common in sports with a lot of planting, cutting, and pivoting, such as soccer, basketball, skiing and football.

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.

Torn ACL Animation Video

Image of knee structures for surgery
Watch an animation of a minimally
invasive ACL reconstruction.

Explore the Torn ACL

deep dive knee - torn acl
View a guided diagram of a torn ACL in the
knee, the supporting structures and anatomy.

Symptoms and Diagnosis

Athletes with an ACL injury often hear or feel a “pop” at the time of injury. The knee will quickly swell, and, in many cases, feel unstable. An ACL injury is often accompanied by other injuries to the knee, such as to cartilage or additional knee ligaments.

A physician 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.


Immediately after ACL injury, it is important to decrease the inflammation in the knee by applying ice and taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. Physical therapy will be critical to strengthen the surrounding muscles and improve the range of motion of the knee.

Some ACL injuries can be treated with physical therapy alone, with patients able to lead an active and healthy lifestyle. However, for athletes who wish to continue to perform at a high level or participate in high-demand activities, ACL reconstruction surgery is often needed.

Since the ACL cannot usually be repaired or reattached once it is torn, surgical reconstruction is required. A graft of replacement tissue, either from the patient’s own hamstring or patellar tendon, or an allograft (human donor tissue) is used to replace the ACL. The reconstruction is performed, using arthroscopic surgery, through several small incisions around the knee.

ACL Surgery Recovery Time

Patients can walk with crutches and a leg brace on the day of surgery. However, it usually takes six months before a person can return to participating in sports after an ACL reconstruction, depending on the level of competition and the type of activity.

Physical therapy will begin immediately. Strengthening and range-of-motion exercises are started early in the recovery period, with progression to running at four months. Pivoting exercises are started around five months, with return to play at six months. Arthroscopy has made the postoperative period easier for the patient, but carefully supervised rehabilitation is critical for a successful outcome.

Below, explore articles and other content on ACL injuries or find the best doctor or surgeon at HSS to suit your specific condition and insurance.

Back in the Game Patient Stories

Specialized Centers, Departments and Services:


Leave a Reply

Your email address will not be published. Required fields are marked *