The effect of patient positioning on the precision of model-based radiostereometric analysis

J Biomech. 2014 Jun 3;47(8):1914-7. doi: 10.1016/j.jbiomech.2014.03.034. Epub 2014 Apr 3.


A repeatable method for in vivo and in vitro measurement of polyethylene wear in total knee replacement (TKA) is needed. This research examines the model-based radiostereometric analysis' (MBRSA) in vitro precision under different patient-radiograph orientations and flexion angles of the knee using a TKA phantom. Anterior-posterior and medial-lateral imaging orientations showed the highest precision; better than 0.036mm (3-dimensional translation) and 0.089° (3-dimensional rotation). Flexion of the knee did not affect MBRSA precision. Medial-lateral imaging is advantageous as it allows for flexion of the knee joint during an RSA examination, thus providing greater information for wear measurement.

Keywords: Micromotion; Phantom; Precision; Radiostereometric analysis; Total knee replacement; Wear analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arthroplasty, Replacement, Knee / methods*
  • Equipment Design
  • Humans
  • Knee Joint / physiology*
  • Knee Joint / surgery*
  • Patient Positioning*
  • Phantoms, Imaging
  • Polyethylene / chemistry*
  • Prosthesis Failure
  • Radiostereometric Analysis*
  • Range of Motion, Articular
  • Reproducibility of Results
  • Rotation


  • Polyethylene