title: Geometric accuracy in robot-assisted total hip replacement surgery.
abstract: OBJECTIVE
  Robot-Assisted Surgery in Total Hip Replacement (RAS-THR) has become a fairly widespread procedure for hip replacement surgery in Europe. However, data on the geometric accuracy of the overall process have so far been unavailable. The equipment manufacturers have only published data on the accuracy of certain elements of the procedure (e.g., the accuracy of the robot system). This study aimed to investigate the overall geometric accuracy of the complete process of RAS-THR, as well as the influence of some of the individual component steps.
  
  
  METHODS
  An anthropomorphic phantom has been developed representing the hip and upper leg region of a human body. The entire RAS-THR procedure can be carried out using this phantom. Studies were conducted to investigate the overall accuracy of the process, as well as the influence of some individual steps in the procedure, using both the ROBODOC and CASPAR systems.
  
  
  RESULTS
  Overall geometric accuracy of the RAS-THR process was found to be within a standard deviation of 0.5 mm and 0.3 degrees in the critical directions. Most individual steps in the process make similar contributions to the overall variation. The two robot systems examined offer comparable accuracy.
  
  
  CONCLUSIONS
  Initial results seem to indicate that the RAS-THR process is acceptably accurate. However, acceptance criteria for the necessary geometric accuracy have not yet been defined.
authors.affiliation: Institute of Medical Physics, Friedrich-Alexander University Erlangen-Nuremberg, Germany. joergschneider@siemens.com
authors.forename: Jörg
authors.initials: J
authors.lastname: Schneider
authors.forename: Willi
authors.initials: W
authors.lastname: Kalender
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D002985:Clinical Protocols; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008328:Man-Machine Systems; D019047:Phantoms, Imaging; D012371:Robotics / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D014057:Tomography, X-Ray Computed