title: Anterior tibiofemoral intersegmental forces during landing are predicted by passive restraint measures in women.
abstract: BACKGROUND
  Passive restraint capabilities may influence sagittal plane knee joint mechanics during activity. This study aimed to determine if measures associated with passive restraint of anterior translation of the tibia are predictive of peak anterior knee shear force during landing.
  
  
  METHODS
  Passive restraint measures were assessed via joint arthrometry and during 40% body weight simulated weight acceptance using recreationally active students (73F, 42M; 21.8±2.9yr, 1.69±0.1m, 68.9±14.1kg). Anterior knee laxity (mm) at 133N and initial (0-20N) and terminal (100-130N) anterior stiffnesses (N/mm) were calculated from arthrometer data. Peak anterior tibial acceleration (m∙s(-2)) relative to the femur was assessed via electromagnetic position sensors during 40% body weight acceptance trials. Peak knee shear force was assessed during double-leg drop jumps.
  
  
  RESULTS
  Sex specific linear stepwise regressions revealed that in females, increasing peak tibial acceleration (5.1±1.8m·s(-2)) (R(2)∆=7.3%, P∆=0.021), increasing initial anterior stiffness (31.0±14.0N/mm) (R(2)∆=5.9%, P∆=0.032), and decreasing terminal anterior stiffness (43.4±17.4N/mm) (R(2)∆=4.9%, P∆=0.046) collectively predicted greater peak knee shear forces (66.6±12.03% BW) (multiple R(2)=18.1%). No male regressions were significant.
  
  
  CONCLUSIONS
  Sagittal laxity measures are associated with anterior knee shear loads during landing in females. Greater tibial acceleration during early axial load along with greater initial and lesser terminal anterior stiffnesses predicted increasing anterior knee shear forces. Future work should investigate the combined contribution of passive and active restraints to high-risk ACL biomechanics.
authors.affiliation: University of North Carolina at Greensboro, Department of Kinesiology, 250 HHP Bldg., Greensboro, NC 27402, USA. Electronic address: rjschmit@uncg.edu.
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Schmitz
authors.forename: Jerome J
authors.initials: JJ
authors.lastname: Sauret
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shultz
mesh_terms: D000054:Acceleration; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000502:physiology*; D053587:Arthrometry, Articular / Q000379:methods; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D007593:Joint Instability / Q000517:prevention & control*; D007719:Knee Joint / Q000502:physiology*; D016014:Linear Models; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular / Q000502:physiology*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013177:Sports / Q000502:physiology*; D013314:Stress, Mechanical; D013977:Tibia / Q000502:physiology*; D055815:Young Adult
keywords: ACL; Laxity; Tibial acceleration