Four main ligaments hold the knee joints together: the medial collateral ligament, lateral collateral ligament, anterior cruciate ligament and posterior cruciate ligament. Injury to the cruciate ligaments is more devastating than the collateral ligaments because the collateral ligaments have some potential for healing without surgery. The cruciate ligaments have virtually no capacity for healing once they are torn.
ACL tears occur two to six times more frequently in females than in males involved in the same amount of sports participation. However, due to the higher level of male participation in contact and collision sports, the overall number of cruciate ligament injuries remains higher in males. ACL injuries can be associated with injuries to meniscal cartilage and the surface cartilage in the knee, which can complicate matters.