An anterior cruciate ligament (ACL) injury is a partial or full tear of the tough band of fibers that connects the lower leg bone to the thigh bone.
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ACL injury is caused by excess force on the knee. This may be from:
This problem in more common in young athletes. It is also more common in athletes who are female. Some sports that may raise the risk are skiing, snowboarding, soccer, and basketball.
Other things that may raise the risk are:
An injury to the ACL may cause:
The doctor will ask about your symptoms, past health, and how the injury happened. A physical exam will be done. It will focus on the knee.
The doctor may suspect an ACL injury based on symptoms. Images may be done to confirm it. This can be done with:
The ACL does not heal on its own. The first steps will be to ease pain and swelling. This can be done with rest, ice, medicine, and elevating the leg.
Active people under 35 years of age may need surgery. It will remake the ACL with tissue from other areas of the body or from donor tissue.
Older adults who are not as active may not need surgery, especially if the knee is stable. Exercises may be given to strengthen the muscles around the knee.
The risk of an ACL injury may be lowered by:
OrthoInfo—American Academy of Orthopaedic Surgeons
Sports Med—American Orthopaedic Society for Sports Medicine
Canadian Orthopaedic Association
Canadian Orthopaedic Foundation
American Academy of Orthopaedic Surgeons (AAOS). Evidence-based clinical practice guideline for management of anterior cruciate ligament injuries. AAOS 2014 Sep 5.
Anterior cruciate ligament (ACL) injury. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/anterior-cruciate-ligament-acl-injury. Accessed March 27, 2021.
Anterior cruciate ligament injuries. Ortho Info—American Academy of Orthopaedic Surgeons website. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00549. Accessed March 27, 2021.
ACL Injury: Does It Require Surgery? American Academy of Orthopaedic Surgeons website. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00297. Accessed March 27, 2021.
Last reviewed February 2021 by EBSCO Medical Review Board Teresa Briedwell, PT, DPT, OCS, CSCS Last Updated: 3/27/2021