title: A mechanical pivot-shift device for continuously applying defined loads to cadaveric knees.
abstract: OBJECTIVE
  Current techniques to study the biomechanics of the pivot-shift utilize either static or poorly defined loading conditions. Here, a novel mechanical pivot-shift device that continuously applies well-defined loads to cadaveric knees is characterized and validated against the manual pivot-shift.
  
  
  METHODS
  Six fresh-frozen human lower limb specimens were potted at the femur, mounted on a hinged testing base, and fitted with the mechanical device. Five mechanical and manual pivot-shift tests were performed on each knee by two examiners before and after transecting the ACL. Three-dimensional kinematics (anterior and internal-rotary displacements, and posterior and external-rotary velocities) and kinetics (forces and moments applied to the tibia by the device) were recorded using an optical navigation system and 6-axis load cell. Analysis of variance and Bland-Altman statistics were used to gauge repeatability within knees, reproducibility between knees, agreement between the mechanical and manual test methods, and agreement between examiners.
  
  
  RESULTS
  The forces and moments applied by the device were continuous and repeatable/reproducible to within 4/10 % of maximum recorded values. Kinematic variables (excluding external-rotary velocity) were qualitatively and quantitatively similar to manual pivot-shift kinematics, and were more repeatable and reproducible.
  
  
  CONCLUSIONS
  The presented device induces pivot-shift-like kinematics by applying highly repeatable three-dimensional loads to cadaver knees. It is based on a simple mechanical principle and designed using easily obtainable components. Consequently, the device enables orthopaedic biomechanists to easily and reliably quantify the effect of ACL injury and reconstruction on pivot-shift kinematics.
authors.affiliation: Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, University of California, San Francisco 1500 Owens Ave, San Francisco, CA, 94158, USA.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Sena
authors.affiliation: Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, University of California, San Francisco 1500 Owens Ave, San Francisco, CA, 94158, USA.|Orthopaedic Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: DellaMaggioria
authors.affiliation: Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, University of California, San Francisco 1500 Owens Ave, San Francisco, CA, 94158, USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Lotz
authors.affiliation: Sports Medicine and Shoulder Surgery, Department of Orthopaedic Surgery, University of California, San Francisco 1500 Owens Ave, San Francisco, CA, 94158, USA. Brian.Feeley@ucsf.edu.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Feeley
mesh_terms: D053587:Arthrometry, Articular / Q000295:instrumentation*; D001696:Biomechanical Phenomena / Q000502:physiology; D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008875:Middle Aged; D015203:Reproducibility of Results; D016474:Weight-Bearing / Q000502:physiology*
keywords: ACL; Device; Force; Moment; Pivot-shift; Rotational instability