Anterior Cruciate Ligament


An ACL tear or injury most commonly occurs during sports that involve sudden stops and changes in direction — such as basketball, soccer, tennis and volleyball.
Depending on the severity of your ACL injury, treatment may include surgery to replace the torn ligament followed by rehabilitation exercises to help you regain strength and stability. If your favorite sport involves pivoting or jumping, a proper training program may help reduce your chances of an ACL injury.


It occurs more often in females than in males, from adolescents to older adults. ACL tears can be associated with meniscal tears or collateral ligament injuries.

Ligaments are strong bands of tissue that connect one bone to another. The ACL, one of two ligaments that cross in the middle of the knee, connects your thighbone (femur) to your shinbone (tibia) and helps stabilize your knee joint.

Most ACL injuries happen during sports and fitness activities. The ligament may tear when you slow down suddenly to change direction or pivot with your foot firmly planted, twisting or hyperextending your knee.

Landing awkwardly from a jump can also injure your ACL, as can falls during downhill skiing. A football tackle or motor vehicle accident also can cause an ACL injury. However, most ACL injuries occur without such contact.


At the time of an ACL injury, signs and symptoms may include:

  • A loud “pop” sound
  • Severe pain and inability to continue activity
  • Knee swelling that usually worsens for hours after the injury occurs
  • A feeling of instability or “giving way” with weight bearing

Most athletes who have torn their ACL will hear or feel a pop accompanied by pain and, soon after, swelling occurs. Rapid swelling in the knee is typically cause by bleeding associated with the injury. The pain might subside quickly after an ACL injury, but this does not mean the tear or strain is healing.

An athlete will experience instability with an insecure sensation while pivoting or loading the knee; an occasional sense of hyper-extension of the knee us also common.Tenderness often occurs at the lateral joint line.

Why Women have greater risk

Women are significantly more likely to have an ACL tear than are men participating in the same sports. Women tend to have a strength imbalance, with the muscles at the front of the thigh (quadriceps) being stronger than the muscles at the back of the thigh (hamstrings). The hamstrings help prevent the shinbone from moving too far forward during activities. When landing from a jump, some women may land in a position that increases stress on their ACL.

What to expect during doctor appointment

During the physical exam, your doctor will check your knee for swelling and tenderness — comparing your injured knee to your uninjured knee. He or she also may move your knee into a variety of positions, to help determine if your ACL is torn.

Often the diagnosis can be made on the basis of the physical exam alone, but you may need tests to rule out other causes and to determine the severity of the injury. These tests may include:

X-rays may be needed to rule out a bone fracture. However, X-rays can’t visualize soft tissues such as ligaments and tendons.

Magnetic resonance imaging (MRI)
An MRI uses radio waves and a strong magnetic field to create images of both hard and soft tissues within your body. An MRI can show the extent of an ACL injury and whether other knee ligaments or joint cartilage also are injured.

Using sound waves to visualize internal structures, ultrasound may be used to check for injuries in the ligaments, tendons and muscles of the knee


Incomplete ACL and PCL tears are treated conservatively to allow the body to hear on its own. Rest, ice, compression and elevation are the immediate treatment. Anti-inflammatory medications and Nsaids can help reduce pain. Physical therapy is often recommended to regain and build muscle strength over time. The most common treatment for a torn ACL is arthroscopic surgery and ACL reconstruction.

Initial treatment for an ACL injury aims to reduce pain and swelling in your knee, regain normal joint movement and strengthen the muscles around your knee.

You and your doctor will then decide if you need surgery plus rehabilitation, or rehabilitation alone. The choice depends on several factors, including the extent of damage to your knee and your willingness to modify your activities.

Athletes who wish to return to sports involving cutting, pivoting or jumping usually pursue surgical reconstruction to prevent episodes of instability. More-sedentary people without significant injury to the cartilage or other ligaments usually can maintain knee stability with rehabilitation alone.

Whether or not you have surgery on your knee, you’ll need rehabilitation. Therapy will include:

  • The use of crutches and, possibly, a knee brace
  • Range-of-motion exercises to regain your full knee motion
  • Muscle-strengthening and stability exercises

A torn ACL can’t be successfully sewn back together, so the ligament is usually replaced with a piece of tendon from another part of your knee or leg. A tendon graft from a deceased donor also may be an option. This surgery is usually performed through small incisions around your knee joint. A narrow, fiber-optic viewing scope is used to guide the placement of the ACL graft.

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Dr Kevin Yip is an orthopaedic surgeon/professor

He has more than 20 years experience in treating orthopaedic problems ranging from common orthopaedic problem, sport injuries to degenerative changes of orthopaedic problem.
Be assured that you will be receiving professional treatments that suit your needs.

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