Anterior cruciate ligament The anterior cruciate ligament ( ACL ) is a cruciate ligament which is one of the four major ligament s of the human knee . In the quadruped stifle ( analogous to the knee ) , based on its anatomical position , it is also referred to as the cranial cruciate ligament . The ACL originates from deep within the notch of the distal femur . Its proximal fibers fan out along the medial wall of the lateral femoral condyle . There are two bundles of the ACL — the anteromedial and the posterolateral , named according to where the bundles insert into the tibial plateau . The ACL attaches in front of the intercondyloid eminence of the tibia , being blended with the anterior horn of the medial meniscus . These attachments allow it to resist anterior translation and medial rotation of the tibia , in relation to the femur . The anterior cruciate ligament is part of what is known as “ the terrible triad ” . This consists of the tearing of the anterior cruciate ligament ( ACL ) , medial collateral ligament ( MCL ) , and medial meniscus all at one time . Injury . The ACL is quite commonly injured in athletes of varying sports . These situations are often remedied by surgery followed by several months of physical therapy . A 2010 Los Angeles Times review of two medical studies discussed whether ACL reconstruction was advisable . One study found that children under 14 who had ACL reconstruction fared better after early surgery than those who underwent a delayed surgery . For adults 18 to 35 , though , patients who underwent early surgery followed by rehabilitation fared no better than those who had rehabilitative therapy and a later surgery . The first report focused on children and the timing of an ACL reconstruction . ACL injuries in children are a challenge because children have open growth plates in the bottom of the femur or thigh bone and on the top of the tibia or shin . An ACL reconstruction will typically cross the growth plates , posing a theoretical risk of injury to the growth plate , stunting leg growth or causing the leg to grow at an unusual angle . The second study noted in the L . A . Times piece focused on adults . It found no significant statistical difference in performance and pain outcomes for patients who receive early ACL reconstruction vs . those who receive physical therapy with an option for later surgery . This would suggest that many patients without instability , buckling or giving way after a course of rehabilitation can be managed non - operatively . However , the study points to the need for more extensive research , was limited to outcomes after 2 years , and did not involve patients who were serious athletes . Patients involved in sports requiring significant cutting , pivoting , twisting , or rapid acceleration or deceleration may not be able to participate in these activities without ACL reconstruction . The randomized control study was originally published in the New England Journal of Medicine . ACL Injuries in Women . Women have been known to suffer ACL injuries more frequently than men ; current research gives some explanations for this . The joint through which the anterior cruciate ligament passes , along with the actual size of the anterior cruciate ligament , is significantly smaller in women than in men . This makes it more susceptible to damage . Along with these aspects , women tend to not activate their hamstring muscles as much as their male counterparts during certain cutting movements causing less stability in the knee joint .