title: The relationship between anterior tibial acceleration, tibial slope, and ACL strain during a simulated jump landing task.
abstract: BACKGROUND
  Knee joint morphology contributions to anterior cruciate ligament (ACL) loading are rarely considered in the injury prevention model. This may be problematic as the knee mechanical response may be influenced by these underlying morphological factors. The goal of the present study was to explore the relationship between posterior tibial slope (which has been recently postulated to influence knee and ACL loading), impact-induced anterior tibial acceleration, and resultant ACL strain during a simulated single-leg landing.
  
  
  METHODS
  Eleven lower limb cadaveric specimens from female donors who had had a mean age (and standard deviation) of 65 ± 10.5 years at the time of death were mounted in a testing apparatus to simulate single-limb landings in the presence of pre-impact knee muscle forces. After preconditioning, specimens underwent five impact trials (mean impact force, 1297.9 ± 210.6 N) while synchronous three-dimensional joint kinetics, kinematics, and relative anteromedial bundle strain data were recorded. Mean peak tibial acceleration and anteromedial bundle strain were quantified over the first 200 ms after impact. These values, along with radiographically defined posterior tibial slope measurements, were submitted to individual and stepwise linear regression analyses.
  
  
  RESULTS
  The mean peak anteromedial bundle strain (3.35% ± 1.71%) was significantly correlated (r = 0.79; p = 0.004; ß = 0.791) with anterior tibial acceleration (8.31 ± 2.77 m/s-2), with the times to respective peaks (66 ± 7 ms and 66 ± 4 ms) also being significantly correlated (r = 0.82; p = 0.001; ß = 0.818). Posterior tibial slope (mean, 7.6° ± 2.1°) was significantly correlated with both peak anterior tibial acceleration (r = 0.75; p = 0.004; ß = 0.786) and peak anteromedial bundle strain (r = 0.76; p = 0.007; ß = 0.759).
  
  
  CONCLUSIONS
  Impact-induced ACL strain is directly proportional to anterior tibial acceleration, with this relationship being moderately dependent on the posterior slope of the tibial plateau.
authors.affiliation: School of Kinesiology, The University of Michigan, 401 Washtenaw Avenue, Ann Arbor, MI 48109, USA. mcleansc@umich.edu
authors.forename: Scott G
authors.initials: SG
authors.lastname: McLean
authors.forename: Youkeun K
authors.initials: YK
authors.lastname: Oh
authors.forename: Mark L
authors.initials: ML
authors.lastname: Palmer
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Lucey
authors.forename: Dustin G
authors.initials: DG
authors.lastname: Lucarelli
authors.forename: James A
authors.initials: JA
authors.lastname: Ashton-Miller
authors.forename: Edward M
authors.initials: EM
authors.lastname: Wojtys
mesh_terms: D000054:Acceleration; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000502:physiology*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000503:physiopathology; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D008422:Materials Testing; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011859:Radiography; D013977:Tibia / Q000000981:diagnostic imaging / Q000502:physiology*