title: Influence of the valgus force during knee flexion in neutral rotation.
abstract: OBJECTIVE
  The pivot shift test is generally accepted to be a clinically useful tool. In the current study, the authors aimed to determine the minimum amount of valgus force required to elicit a positive pivot shift test utilizing a mechanized pivot shifter device in ACL-deficient knees. The authors proposed that increasing the applied force from a minimum critical value would lead to greater magnitudes of femoro-tibial translation.
  
  
  METHODS
  Six fresh-frozen pelvis-to-toes specimens were used in this cadaveric study. Tracking and recording of tibiofemoral kinematics during throughout testing was achieved by an image-free surgical navigation system with dedicated ACL software. A load cell was attached to the mechanized pivot shifter through a three-degree-of-freedom arm. Valgus force magnitudes of 0-5 kg were then sequentially applied, and knee flexion in neutral rotation was performed on the ACL-deficient knees. A total of two trials were performed for each force.
  
  
  RESULTS
  The greatest difference in lateral and medial compartment translation, during the pivot shift test, utilizing a mechanized pivot shifter in an ACL-deficient knee, was measured between an applied valgus force of 0 and 1 kg. The mean difference between 4 and 5 kg was 0.2 mm (CI = -11.29 to 10.89) for the lateral compartment, and there was no difference in translation for the medial compartment (CI = -17.43 to 17.43).
  
  
  CONCLUSIONS
  The principal finding of the current study was that a greater force does not produce a greater magnitude of femoro-tibial translation during knee flexion in neutral rotation, contrary to the initial hypothesis.
authors.affiliation: Trauma Department, Hannover Medical School, Carl-Neuberg St. 1, 30625, Hannover, Germany. citak.musa@mh-hannover.de
authors.forename: Musa
authors.initials: M
authors.lastname: Citak
authors.forename: Padhraig F
authors.initials: PF
authors.lastname: O'Loughlin
authors.forename: Mustafa
authors.initials: M
authors.lastname: Citak
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Suero
authors.forename: Marianne R F
authors.initials: MR
authors.lastname: Bosscher
authors.forename: Volker
authors.initials: V
authors.lastname: Musahl
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Pearle
mesh_terms: D016118:Anterior Cruciate Ligament / Q000502:physiology*; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D016059:Range of Motion, Articular; D012399:Rotation
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