Recovery from an anterior cruciate ligament (ACL) tear typically takes 3–12 months, depending on injury severity and goals for rehabilitation.

The knee comprises three bones—the femur or thighbone, the tibia or shinbone, and the patella or kneecap. Tendons join muscles to these bones, while ligaments hold the three bones in place. These ligaments protect the knee joint from excessive rotation. The ACL is one of the ligaments that stabilize the knee joint.

ACL tears are the most common knee ligament injury, occurring in around 1 in 3,500 people in the United States. This injury is common in people who play sports involving sudden direction changes and jumping.

Treatment of an ACL tear depends on the severity of the ligament damage and the person’s health. This article explains how doctors treat ACL injuries and how long recovery takes.

Learn more about the knee here.

A person using a treadmill after recovering from a torn ACL.Share on Pinterest
Kriangkrai Thitimakorn/Getty Images

Doctors recommend treatment based on the severity of the ACL injury and the person’s overall health, including their ability to recover from surgery.

There are two methods for treating an ACL injury:

Nonsurgical treatment

People with partial tears and minimal knee instability may opt for nonsurgical treatment. It may also be appropriate for people who live inactive lifestyles.

The RICE method involves rest, ice, knee compression, and lower leg elevation. Doctors will likely recommend progressive physical therapy to regain strength and improve knee function and stability. People may also wear a knee brace to provide extra support during recovery.


Doctors often recommend surgery for people with complete ACL tears or other injuries to the knee. Active people and young children, in particular, may benefit from surgery.

Surgery involves the reconstruction of the ACL ligament using a substitute graft made from a tendon from elsewhere in the body, such as the hamstring or quadriceps. Sometimes, the graft is from a tissue donor.

Surgeons repair damaged ACLs in a procedure called arthroscopy. This is less invasive than open surgery and avoids the need to make large cuts through soft tissue.

Learn more about knee arthroscopy here.

According to the American Academy of Orthopedic Surgeons (AAOS), recovery from a partially torn ACL usually lasts at least 3 months.

People should avoid bearing weight on their injured limb during that time, using crutches or a wheelchair if necessary. Doctors may also recommend pain-relief medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs).

Physical therapy is important for people who do not have surgery. It can help improve knee function and stability. According to a 2022 article, around half of people who do not initially have surgery later choose to have surgical repair.

Following surgery, a doctor may prescribe pain-relief medications, such as NSAIDs.

Physical therapy is crucial to ensure a person’s ACL repair surgery is successful. They should begin exercises immediately after the surgery.

Exercises in the first 7–10 days aim to help the person straighten their leg and restore quadriceps control. Regularly icing the joint can reduce swelling and pain.

A doctor will assess a person’s ability to bear weight on their injured limb and may recommend using crutches or wearing a knee brace.

The individual may return to light activity, such as walking and climbing stairs before the swelling has gone down and full strength has returned, but a person cannot return to sport until:

  • there is no swelling or pain
  • they have a full range of motion in the knee
  • they have good muscle strength and endurance
  • the knee functions well
  • they have good balance and leg control

People who have undergone ACL repair surgery can often return to sports and other activities after 6–12 months. However, this depends on the injury severity and how they commit to physical therapy after the surgery.

After surgical repair, 90% of people return to pre-injury functioning. Fear of reinjury may hold some people back from pre-injury activity levels.

Surgery to treat an ACL injury is a common procedure, with good outcomes in 75–97% of people.

However, potential problems that can occur with surgical treatment include:

  • Stiffness: Performing surgery too soon after the injury has occurred and not ensuring correct physical therapy to reduce swelling before surgery can result in a poor range of movement.
  • Infection: A contaminated graft during surgery can increase the risk of infection.
  • Nerve injury: Nerve injury can occur, which results in numbness in certain regions of the knee joint.
  • Patella fracture: The patella can weaken after surgeons take a ligament graft from it. This makes it more prone to fracture during recovery from surgery.
  • Blood clots. While rare, a blood clot in the veins of the leg can be a fatal complication of surgery. If a clot breaks away and travels to the lungs, this can result in a pulmonary embolism.

Learn more about the causes, types, diagnosis, and prevention of ACL injuries here.

Depending on the type of treatment, recovery from an ACL injury can take 3–12 months. Recovery depends largely on injury severity and a person’s commitment to physical therapy and rehabilitation.

An individual with an ACL tear is at greater risk of developing knee osteoarthritis (OA). According to the Arthritis Foundation, 87% of people with an ACL injury develop OA.

The ACL is a ligament that helps stabilize the knee. Torn ACLs are the most common knee ligament injury and often happen to people who play certain sports.

Treatment can be nonsurgical or surgical. People with mild ACL tears or inactive lifestyles may opt for nonsurgical treatment.

Knee arthroscopy surgery is usually successful and helps restore the function and stability of the knee.

Physical therapy following an ACL injury is crucial in the recovery period. A physical therapist will develop a program of exercises tailored to an individual.

A person with an ACL injury has a higher risk of future knee injury and OA. People may wish to ask a physical therapist how to reduce their risk.