Anterior Cruciate Ligament (ACL)
What Is an ACL Tear?
The anterior cruciate ligament, or ACL, is an important ligament in the knee that helps provide stability during movement. It connects the thigh bone to the shinbone and helps control forward and rotational movement of the knee.
An ACL tear can happen during sports, exercise or another activity that places significant stress on the knee. Injuries often occur during movements that involve sudden changes in direction, pivoting, stopping or landing.
An ACL injury can range from a sprain to a complete tear. Treatment depends on the severity of the injury, how it affects knee stability, your activity level and whether other structures in the knee are also injured.
What Are the Symptoms of an ACL Tear?
ACL tear symptoms can vary depending on the severity of the injury and whether other parts of the knee are injured. Some people hear or feel a popping sensation when the injury occurs, followed by pain, swelling or difficulty continuing the activity.
Symptoms may include:
- A popping sound or sensation at the time of injury
- Knee pain
- Swelling
- Reduced range of motion
- Difficulty putting weight on the injured knee
- A feeling that the knee is unstable or may give way
If a knee injury causes significant pain, swelling, instability or difficulty walking, an orthopedic evaluation can help determine what was injured and which treatment may be appropriate.
How Is an ACL Tear Diagnosed?
Diagnosing an ACL injury begins with a review of how the injury happened, your symptoms and a physical examination of the knee. Your health care provider will assess knee movement and stability and look for signs of injury to the ACL or other structures in the knee.
Imaging may also be recommended depending on your injury and examination findings. An MRI may be used to evaluate the ACL and other soft tissues in the knee and identify injuries that occur along with an ACL tear.
Your orthopedic specialist will use your history, examination findings and imaging when needed to determine the severity of the injury and recommend treatment.
ACL Tear Treatment
Treatment for an ACL tear depends on the severity of the injury, how stable your knee is, your activity level, your goals and whether other structures in the knee are also injured.
Some ACL injuries can be treated without surgery, while other patients may benefit from ACL reconstruction. Physical therapy and rehabilitation are important parts of treatment in both nonsurgical and surgical care.
Nonsurgical ACL Tear Treatment
Nonsurgical treatment may be appropriate for some patients depending on knee stability, activity needs and the extent of the injury. Treatment is designed to reduce symptoms, restore movement and strengthen the muscles that support the knee.
Your treatment plan may include:
- Rest and temporary activity modification
- Ice to help manage pain and swelling
- Compression and elevation when recommended
- Bracing when appropriate
- Physical therapy to improve strength, range of motion, balance and knee function
Nonsurgical ACL Tear Treatment
Nonsurgical treatment may be appropriate for some patients depending on knee stability, activity needs and the extent of the injury. Treatment is designed to reduce symptoms, restore movement and strengthen the muscles that support the knee.
Your treatment plan may include:
- Rest and temporary activity modification
- Ice to help manage pain and swelling
- Compression and elevation when recommended
- Bracing when appropriate
- Physical therapy to improve strength, range of motion, balance and knee function
ACL Reconstruction Surgery
ACL reconstruction may be considered when the injury causes ongoing knee instability or when returning to an activity requires greater knee stability. The decision also depends on factors such as your activity level, other knee injuries and individual treatment goals.
During ACL reconstruction, the injured ligament is replaced with a tendon graft. The graft may come from tissue in your own body or from donor tissue. Your orthopedic surgeon will discuss graft options and recommend an approach based on your individual needs.
ACL reconstruction may be considered for patients who:
- Want to return to sports or activities that involve cutting, pivoting or jumping
- Continue to experience knee instability
- Have additional injuries involving other structures in the knee
- Need greater knee stability for work, sports or everyday activities
What Happens During ACL Reconstruction?
ACL reconstruction is typically performed using small incisions and arthroscopic surgical techniques. An arthroscope is a small camera that allows the surgeon to view structures inside the knee while performing the procedure.
Arthroscopy may also allow the surgeon to evaluate or treat other structures in the knee when appropriate. Your surgeon will explain the procedure and any additional knee injuries that may need to be addressed.
ACL Tear Rehabilitation and Recovery
Rehabilitation is an important part of recovery after an ACL injury, whether treatment involves surgery or a nonsurgical approach. Physical therapy is used to help restore knee movement, build strength and improve stability and function.
Rehabilitation progresses gradually based on your injury, treatment and response to therapy. Your physical therapist may guide you through exercises designed to improve range of motion, leg strength, balance, movement control and functional activities.
Returning to running, sports or other high-demand activities requires more than simply waiting for a certain amount of time. Your care team will evaluate your strength, knee function, movement and progress before recommending a return to specific activities.
Can ACL Injuries Be Prevented?
Not every ACL injury can be prevented, but training focused on movement technique, strength and neuromuscular control may help reduce the risk of certain noncontact ACL injuries.
Injury-prevention programs may focus on jumping and landing technique, change-of-direction mechanics, balance, strength and movement control. Athletes should follow a program appropriate for their age, sport and activity level.
Frequently Asked Questions About ACL Tears
Some people with an ACL injury can be treated without surgery. Whether nonsurgical treatment is appropriate depends on factors such as the extent of the injury, knee stability, your activity needs and whether other structures in the knee are injured.
An orthopedic specialist can evaluate your knee and recommend a treatment plan based on your individual needs.
Some people are able to walk after an ACL injury, but the knee may feel painful, swollen or unstable. Being able to walk does not indicate how severe the injury is or whether other parts of the knee are injured.
If your knee gives way or you have significant pain, swelling or difficulty moving it, seek medical evaluation.
No. Treatment depends on knee stability, the extent of the injury, your activity level and goals, and other injuries in the knee. Some patients may do well with rehabilitation and nonsurgical management, while others may benefit from ACL reconstruction.
ACL recovery varies depending on the severity of the injury, the treatment you receive and your progress with rehabilitation. Recovery after ACL reconstruction typically involves several stages before returning to running or sports.
Your care team will assess strength, knee function and movement as rehabilitation progresses rather than relying on time alone.
Many patients work toward returning to sports after an ACL injury, but readiness depends on recovery, strength, knee stability and completion of appropriate rehabilitation. Returning too soon may increase the risk of another injury.
Your orthopedic and rehabilitation teams can guide a safe progression based on your sport and individual recovery.