ACL Tear


One of the most common knee injuries is an anterior cruciate ligament (ACL) sprain or tear. Young athletes who participate in sports like soccer, football, and basketball are more likely to injure an ACL. If your child has injured the anterior cruciate ligament, they may require surgery to regain full function of the knee.

Causes & Risk Factors

The ACL can be injured in several ways:

  • Changing direction rapidly
  • Stopping suddenly
  • Slowing down while running
  • Landing from a jump incorrectly
  • Direct contact or collision, such as a football tackle

According to the American Academy of Orthopaedic Surgeons (AAOS): “Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes in certain sports. It has been proposed that this is due to differences in physical conditioning, muscular strength, and neuromuscular control. Other suggested causes include differences in pelvis and lower extremity (leg) alignment, increased looseness in ligaments, and the effects of estrogen on ligament properties.”1


When a young athlete injures the ACL, they might hear a "popping" noise and feel the knee give out. Other common symptoms include:

  • Pain with swelling. In the first day after the injury, the knee will become swollen. The swelling and pain may go away on its own. But if the patient attempts to return to sports, the knee will likely be unstable and risk further damage to the cushioning cartilage (meniscus) of the knee.
  • Loss of full range of motion
  • Tenderness along the joint line
  • Discomfort while walking

Diagnosis & Tests

If the doctor suspects the child has a torn ACL, additional tests will be ordered:

X-rays: An X-ray takes a picture of the athlete's knee and can show whether the bone has been damaged by the injury. This will not, however, show soft tissues such as ligaments or tendons.

Magnetic Resonance Imaging (MRI): The MRI scan creates an image of the knee area using powerful magnets and a computer. The images produced show high-resolution pictures of both bones and soft tissues, like ligaments, and are very useful in diagnosing ACL tears.

Treatment & Care

At Texas Children’s Hospital, our physicians may prefer to treat ACL injuries with methods that do not require surgery, such as physical therapy. Surgery is required in most cases, however, in order to make the knee stable enough to return to sports.

During surgery, orthopedic surgeons take tissue from your child’s hamstring tendons or patellar tendon and use it to reconstruct the ACL. If there are any additional injuries to other structures in the knee, they can be addressed at that time.

Living & Managing

Surgery is always followed by physical therapy that can last up to 9 to 12 months. The return to sports will be determined by the surgeon and the recommendation of the therapist. An early return to sports will likely re-rupture the ACL graft and may require additional surgery.

References & Sources

1American Academy of Orthopaedic Surgeons. “Anterior Cruciate Ligament Injuries.”