title: Accuracy of imageless stem navigation during simulated total hip arthroplasty.
abstract: OBJECTIVE
  New computer-assisted measurement algorithms have been established to support the surgeon during total joint replacement intraoperatively. We asked whether the assessment of leg length and offset measured with an imageless navigation system is reliable during simulated total hip arthroplasty in a sawbone model test bench.
  
  
  RESULTS
  We found no statistically significant difference between change in leg length and offset measured on a millimeter scale connected to the test bench and that obtained with the calculation algorithm of the imageless navigation system.
  
  
  CONCLUSIONS
  Measurement of leg length and offset with an imageless navigation system is reliable during simulated total hip arthroplasty. The leg length situation algorithm offers the advantage of measuring leg length and offset by determination of the change in position of the femur relative to the pelvic coordinate system without the need to calculate the center of rotation of the hip joint. Further studies should address the accuracy of this imageless stem navigation method in an anatomical and clinical setting.
authors.affiliation: Department of Orthopedic Surgery, Regensburg University Medical Center, Bad Abbach, Germany. tobias.renkawitz@web.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Renkawitz
authors.forename: Ernst
authors.initials: E
authors.lastname: Sendtner
authors.forename: Joachim
authors.initials: J
authors.lastname: Grifka
authors.forename: Thomas
authors.initials: T
authors.lastname: Kalteis
mesh_terms: D000465:Algorithms; D019644:Arthroplasty, Replacement, Hip / Q000379:methods; D003198:Computer Simulation; D006801:Humans; D007866:Leg / Q000033:anatomy & histology; D025321:Surgery, Computer-Assisted