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ACL FAQs

  1. What is the anterior cruciate ligament (ACL)?  
  2. How does injury occur to the anterior cruciate ligament?  
  3. How do I know if I have an ACL injury?  
  4. How is an ACL injury diagnosed?  
  5. How is an ACL injury treated?  
  6. Can I resume sports after ACL surgery?  
  7. Can injury to the anterior cruciate ligament happen again?

1. What is the anterior cruciate ligament (ACL)?
The ACL is one of four ligaments in the knee that helps stabilize the knee joint. The ACL and the posterior cruciate ligament (PCL) are positioned in the middle of the joint and cross over one another. These ligaments keep the knee bones — tibia and femur — from sliding forward or under one another, thus keeping the knee in alignment.

The most common ligament injury in the knee is to the ACL. Depending on the extent of the injury, damage also can occur to the PCL, the cartilage (meniscus) and to two other stabilizing ligaments in the knee: the medial collateral ligament (MCL) and the lateral collateral ligament (LCL). These two ligaments are positioned along the inner and outer part of the knee, respectively.

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2. How does injury occur to the anterior cruciate ligament?
ACL tears can occur either from contact or non-contact injury. Contact injuries involve a direct blow to the knee, often with damage to other ligaments as well. Non-contact injuries are the source of over 70 percent of ACL ruptures. They usually occur during deceleration or pivoting of the knee.

3. How do I know if I have an ACL injury?
A large percentage of patients have reported hearing a "pop" in the knee when the ligament ruptures. Swelling in the knee occurs in nearly all ACL tears. The swelling may not be significant and the onset may be delayed for 6 to 24 hours. Swelling within 24 hours of an acute injury means there is blood in the knee and medical attention should be sought.

If the torn or ruptured ACL is not surgically repaired, the patient may experience repetitive instability bouts with the knee buckling and giving way. These difficulties occur in 80 to 90 percent of patients who attempt to return to aggressive physical activities.

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4. How is an ACL injury diagnosed?
The diagnosis of an ACL tear is made in most cases by reviewing a patient's history as well as a thorough physical examination that may include X-rays or an MRI.

5. How is an ACL injury treated?
In active individuals, the recommended treatment for an ACL tear is typically surgical reconstruction. Current techniques have achieved well over 90 percent success in restoring stability to the knee. The current standard of care is to reconstruct the ligament with another piece of tissue because studies have shown a high failure rate with repair of the torn ligament itself.

The surgeons at Virginia Mason Sports Medicine have extensive experience in the use of all the currently used tissues for ACL replacement. These include the patient's own tissue, including patellar tendon grafts, hamstring grafts or quadriceps tendon grafts. Our surgeons also have extensive experience using transplant tissue, which avoids the need to remove portions of the patient's own normal tissue. Your surgeon will thoroughly discuss the pros and cons of each graft option and determine with you the best graft for your knee.

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6. Can I resume sports after ACL surgery?
Yes, after an extensive rehabilitation program, which begins two days after surgery with early strengthening and weight-bearing exercises. It is a critical part of recovery to fully participate in a guided rehabilitation program that incrementally increases strength and activity. Regaining control and strength in the knee is critical in preventing reinjuring the knee when returning to sports. Patients are advised to protect the graft from aggressive sports activities for six to eight months after reconstruction. No matter how quickly you recover from surgery, the graft is undergoing a remodeling process that weakens it. It gradually regains strength over six to eight months. Returning to sports prior to this increases the risk of rupturing the graft.

7. Can injury to the anterior cruciate ligament happen again?
Yes, both amateur and professional athletes have reinjured the reconstructed knee even after an extensive rehabilitation program. Patients are advised to follow their rehabilitation program closely and not resume aggressive sports activities too soon. Your surgeon will answer specific questions about returning to active sports participation.

To schedule an appointment to speak with a sports medicine physician about an injury to your ACL or any other concern, call (206) 341-3000.

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