title: Hip extension, knee flexion paradox: a new mechanism for non-contact ACL injury.
abstract: Considering that an athlete performs at-risk sports activities countless times throughout the course of his or her career prior to the instance of anterior cruciate ligament (ACL) injury, one may conclude that non-contact ACL injury is a rare event. Nevertheless, the overall number of non-contact ACL injuries, both in the US and worldwide, remains alarming due to the growing number of recreational and professional athletes participating in high-risk activities. To date, numerous non-contact ACL injury mechanisms have been proposed, but none provides a detailed picture of sequence of events leading to injury and the exact cause of this injury remains elusive. In this perspective article, we propose a new conception of non-contact ACL injury mechanism that comprehensively integrates risk factors inside and outside the knee joint. The proposed mechanism is robust in the sense that it is biomechanically justifiable and addresses a number of confounding issues related to ACL injury.
authors.affiliation: Texas Tech University, Department of Mechanical Engineering, Lubbock, TX 79409, USA. javad.hashemi@ttu.edu
authors.forename: Javad
authors.initials: J
authors.lastname: Hashemi
authors.forename: Ryan
authors.initials: R
authors.lastname: Breighner
authors.forename: Naveen
authors.initials: N
authors.lastname: Chandrashekar
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Hardy
authors.forename: Ajit M
authors.initials: AM
authors.lastname: Chaudhari
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shultz
authors.forename: James R
authors.initials: JR
authors.lastname: Slauterbeck
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Beynnon
mesh_terms: D016118:Anterior Cruciate Ligament / Q000503:physiopathology*; D000070598:Anterior Cruciate Ligament Injuries; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D007718:Knee Injuries / Q000209:etiology / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular