The anterior cruciate ligament (ACL) is one of the most important ligaments in the knee. It runs diagonally across the middle of the knee and keeps the tibia from sliding out of place. The ACL also provides stability when your knee rotates. A torn ACL refers to the tearing of this ligament and is one of the most common injuries of the knee, along with ACL strains. Partial tears of the ACL are rare; most torn ACLs are complete or near complete tears.
A torn ACL increases the risk of developing osteoarthritis of the knee.
Torn ACL symptoms come on quickly. They may include:
- A notable “pop” sound or “popping” sensation in the knee
- Severe pain
- Inability to continue on with activity
- Feeling of instability or the knee “giving out”
- Swelling, usually within a few hours of the injury
- Loss of range of motion
Symptoms of torn ACL are usually sudden and severe enough to interfere with walking or bearing weight on the injured leg.
A torn ACL is most often caused while participant in a sports or fitness activity that places excessive stress on the knees.
A torn ACL can be caused by any of the following:
- A sudden change of direction, often referred to in sports as “cutting”
- Stopping suddenly
- Landing incorrectly after a jump
- Pivoting while your foot remains firmly planted
- Direct contact that results in a hard blow to the knee
There are certain factors that can increase your risk of a torn ACL. These risk factors include:
Being an athlete.
A torn ACL most often occurs during sports. Being an athlete raises your risk.
Women have been found more likely to suffer ACL injuries than men. Studies suggest that this is a combination of an imbalance of strength in the quadriceps and hamstrings, and landing techniques used by female athletes.
Poor technique in sports activities increases the risk of ACL injuries, including a torn ACL.
ACL injury is more common between the ages of 15 and 45. This is believed to be due to people being most active at this age and participating more in the types of sporting activities associated with an increased risk.
Your doctor will take your medical history when diagnosing a torn ACL. You will be asked to describe your pain and other symptoms, as well as provide details about how the injury occurred. A physical examination will help the doctor diagnose the cause of your symptoms and decide what other tests should be recommended.
During the physical examination, the doctor will inspect your knee’s appearance and compare it to your other knee. He or she will look for tenderness, swelling and other signs of injury. By manipulating your knee into various positions, the doctor will be able to evaluate your joint’s function and range of motion.
Diagnostic imaging tests can help your doctor determine the severity of your injury while also ruling out other causes of symptoms similar the symptoms of a torn ACL.
Imaging tests may include:
X-ray is often used first to rule out fractures and other bone abnormalities that may cause pain. X-rays don’t show soft tissues, such as tendons and ligaments and will not show a torn ACL.
An ultrasound captures real-time images of structures inside the body and can be used to check for damage to the tendons, muscles, and ligaments of the knee.
Magnetic resonance imaging (MRI).
An MRI scan creates highly detailed 3-D images of your bones and soft tissues. It can be used to effectively diagnose a torn ACL and assess the severity of the tear, as well as detect injury to other parts of the knee.
Getting prompt treatment can help relieve torn ACL symptoms, such as pain and inflammation.
The following are options for treating a torn ACL:
Stay off your leg.
Rest your leg to avoid putting weight on the knee. Elevating your knee can also help reduce swelling.
Ice the knee.
Applying an ice pack to the knee can help reduce the swelling.
Brace the knee.
Wrap the knee with an elastic bandage or a knee brace to help stabilize the joint and prevent further injury.
Nonsteroidal anti-inflammatories (NSAIDs), such as Aleve, Advil, and Motrin will reduce inflammation and provide pain relief. Prescription strength NSAIDs may be given if non-prescription medications aren’t sufficient.
Rehabilitative exercises can strengthen the muscles that support the knee and help you regain function.
Surgery may be recommended if you’ve injured more than one of the ligaments or cartilages in the knee. Your doctor may also recommend surgery if you’re an athlete and want to continue to participate in a sport or if you’re young and fairly active. Surgery may be put off until the inflammation has improved. Having the surgery too often can increase the risk of a scar formation in the joint. ACL reconstruction surgery entails removing the damaged tissue and replacing it with a piece of tendon that comes from another part of your knee or from a deceased donor so that the tissue can grow.
The best treatment for you will depend on factors such as your age and activity level, as well as the extent of your injury. Nonsurgical options are the least invasive and therefore the preferred choice when possible. Surgery to repair a torn ACL involves a lengthy recovery and rehabilitative therapy to restore function and stability to the knee. In most cases, you can return to your regular activities, including sports, eight to 12 months following successful ACL surgery.
Recovery time can be significantly reduced when the surgery is performed arthroscopically. Arthroscopic surgery is less invasive than traditional open surgery and is performed using one or two dime-sized incisions and a thin instrument with a camera on the end to visualize and repair the injury. Recovery time for repairing a torn ACL arthroscopically takes just 4 to 6 months.
A torn ACL, even when repaired surgically, increases the risk of developing osteoarthritis of the knee in the future.