The anterior cruciate ligament (ACL) is one of the ligaments in the center of the knee that provides rotational stability to the knee joint and also limits anterior translation of the tibia (shin bone) relative to the femur (thigh bone). ACL tears are typically a result of a non-impact injury in which the knee falls inward while rotating. Because ACL tears often lead to recurrent instability episodes, which can result in irreversible damage to the cartilage and meniscus in the knee, surgery is usually recommended.
While the ACL can sometimes be repaired, the most predictable option is to reconstruct the ACL by transferring tendons or ligaments, such as the patella, quadriceps, or hamstring tendons, from another part of the knee. The goal of this surgery is to stabilize the knee to prevent further damage to the knee cartilage or menisci. It also allows for a high rate of return to sport and other activities that involve rotational and pivoting movements.
- Knee instability/buckling
- Sensation of the knee giving way
- Knee pain
- Knee swelling
- Knee stiffness and decreased range of motion due to pain and swelling
- Physical Therapy - A formal course of physical therapy is often required before surgery to regain the knee range of motion and strength. This is called prehab and has been shown to improve knee range of motion and recovery after surgery.
- Bracing - A knee brace is often used after an ACL injury to prevent any recurrent instability events that could potentially cause further damage to the knee structures such as the menisci and cartilage. In rare cases, patients can wear a knee brace for more vigorous activities as opposed to having the ACL reconstructed.
- Anti-inflammatories - Nonsteroidal anti-inflammatory medications such as Ibuprofen or Aleve can help decrease inflammation and pain caused by a meniscus tear. This can be beneficial in addition to physical therapy, so patients can have less pain while regaining their motion and strength. Prescription-strength anti-inflammatory medications are occasionally prescribed if over-the-counter medications are not working.
- Surgery - For the vast majority of patients, ACL reconstruction is recommended to restore the knee stability and function. This prevents future instability events, which can lead to meniscus tears and irreversible damage to the cartilage. Patients who desire to return to an active lifestyle should strongly consider ACL reconstruction as this is the best option to restore their function and quality of life.
ACL tears typically occur from an acute non-impact injury such as cutting or pivoting. This usually results in a pop with severe pain and swelling. Patients also often have the sensation of instability. After taking a detailed history and a thorough exam, x-rays are obtained to evaluate the knee alignment and for any fractures. MRIs are ordered to confirm the clinical diagnosis of an ACL tear and to also evaluate the menisci, cartilage, and other ligaments in the knee.
The vast majority of patients are recommended for surgery to stabilize the knee, which allows for return to previous activities with confidence. Sedentary patients who are not involved in cutting or pivoting activities or older patients with arthritis may elect for nonoperative treatment. Nonoperative management of ACL injuries in younger and more active patients is not recommended as recurrent instability of the knee can lead to irreversible damage to the cartilage in the knee and meniscus tears.
The most common risks are recurrent instability events, which can lead to irreversible cartilage injury and meniscus tears. Having a nonfunctional ACL also makes it very difficult to return to pivoting sports or activities. Patients who have had an ACL tear have a higher rate of arthritis compared to patients who have not, even if the ACL is reconstructed.