title: Relationship between geometry of the extensor mechanism of the knee and risk of anterior cruciate ligament injury.
abstract: The complex inter-segmental forces that are developed across an extended knee by body weight and contraction of the quadriceps muscle group transmits an anteriorly directed force on the tibia that strain the anterior cruciate ligament (ACL). We hypothesized that a relationship exists between geometry of the knees extensor mechanism and the risk of sustaining a non-contact ACL injury. Geometry of the extensor mechanism was characterized using MRI scans of the knees of 88 subjects that suffered their first non-contact ACL injury and 88 matched control subjects with normal knees that were on the same team. The orientation of the patellar tendon axis was measured relative to the femoral flexion-extension axis to determine the extensor moment arm (EMA), and relative to tibial long axis to measure coronal patellar tendon angle (CPTA) and sagittal patellar tendon angle (SPTA). Associations between these parameters and ACL injury risk were tested with and without adjustment for flexion and internal rotation position of the tibia relative to the femur during MRI data acquisition. After adjustment for internal rotation position of the tibia relative to the femur there were no associations between EMA, CPTA, and SPTA and risk of suffering an ACL injury. However, increased internal rotation position of the tibia relative to the femur was significantly associated with increased risk of ACL injury in female athletes both in univariate analysis (Odds Ratio = 1.16 per degree of internal rotation of the tibia, p = 0.002), as well as after adjustment for EMA, CPTA, and SPTA.: © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:965-973, 2017.
authors.affiliation: McClure Musculoskeletal Research Center, Department of Orthopedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont.
authors.forename: Josh C
authors.initials: JC
authors.lastname: Carter
authors.affiliation: Hospital for Special Surgery, Department of Biomechanics, New York, New York.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Sturnick
authors.affiliation: Department of Medical Biostatistics, University of Vermont, Burlington, Vermont.
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Vacek
authors.affiliation: Department of Medical Biostatistics, University of Vermont, Burlington, Vermont.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: DeSarno
authors.affiliation: McClure Musculoskeletal Research Center, Department of Orthopedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont.
authors.forename: Erin C
authors.initials: EC
authors.lastname: Argentieri
authors.affiliation: McClure Musculoskeletal Research Center, Department of Orthopedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont.
authors.forename: James R
authors.initials: JR
authors.lastname: Slauterbeck
authors.affiliation: McClure Musculoskeletal Research Center, Department of Orthopedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Johnson
authors.affiliation: McClure Musculoskeletal Research Center, Department of Orthopedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Beynnon
mesh_terms: D000293:Adolescent; D000070598:Anterior Cruciate Ligament Injuries / Q000209:etiology*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D015999:Multivariate Analysis; D012307:Risk Factors; D012399:Rotation; D055815:Young Adult
keywords: anterior cruciate ligament injury risk factor; extensor moment arm; femur; morphometrics; patellar tendon