title: Anteroposterior and rotational stability in fixed and mobile bearing unicondylar knee arthroplasty: a cadaveric study using the robotic force sensor system.
abstract: OBJECTIVE
  Different bearing designs in unicondylar knee arthroplasty (UKA) have been developed in order to influence the rate of polyethylene wear. Increased anteroposterior translation and rotation after UKA has been hypothesized due to changes in joint surface geometry. The mobile bearing design was expected to show increased anteroposterior translation compared to the fixed bearing and biconcave bearing design.
  
  
  METHODS
  Six human cadaver knees were used for the tests. Anteroposterior and rotational knee stability was analysed in 0°, 30°, 60°, 90° and 120° of knee flexion using a robotic testing system (KR 125, KUKA Robots Augsburg, Germany). Three forces and moments were measured in a Cartesian coordinate system with a resolution of 1.0 N and 0.1 Nm.
  
  
  RESULTS
  There was no difference between the native knees and the knees after UKA in AP translation and rotation in all knee flexion angles. The factor knee flexion angle had a significant impact on the anterior translation when the type of bearing was neglected (p ≤ 0.015).
  
  
  CONCLUSIONS
  This study shows that the natural knee stability in AP translation and rotation can be preserved in UKA. The preserved knee stability in different planes after UKA underlines the advantage of UKA when surgery is required in osteoarthritic changes of the medial compartment.
authors.affiliation: Department of Orthopaedic and Trauma Surgery, City Hospital Brandenburg, Hochstrasse 26, 14770, Brandenburg, Havel, Germany, roland_becker@yahoo.de.
authors.forename: Roland
authors.initials: R
authors.lastname: Becker
authors.forename: Christian
authors.initials: C
authors.lastname: Mauer
authors.forename: Christian
authors.initials: C
authors.lastname: Stärke
authors.forename: Mathias
authors.initials: M
authors.lastname: Brosz
authors.forename: Thore
authors.initials: T
authors.lastname: Zantop
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Lohmann
authors.forename: Martin
authors.initials: M
authors.lastname: Schulze
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology* / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery*; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012371:Robotics / Q000295:instrumentation*; D012399:Rotation