title: A cost-effective surgical navigation solution for periacetabular osteotomy (PAO) surgery.
abstract: OBJECTIVE
  To evaluate a low-cost, inertial sensor-based surgical navigation solution for periacetabular osteotomy (PAO) surgery without the line-of-sight impediment.
  
  
  METHODS
  Two commercial inertial measurement units (IMU, Xsens Technologies, The Netherlands), are attached to a patient's pelvis and to the acetabular fragment, respectively. Registration of the patient with a pre-operatively acquired computer model is done by recording the orientation of the patient's anterior pelvic plane (APP) using one IMU. A custom-designed device is used to record the orientation of the APP in the reference coordinate system of the IMU. After registration, the two sensors are mounted to the patient's pelvis and acetabular fragment, respectively. Once the initial position is recorded, the orientation is measured and displayed on a computer screen. A patient-specific computer model generated from a pre-operatively acquired computed tomography scan is used to visualize the updated orientation of the acetabular fragment.
  
  
  RESULTS
  Experiments with plastic bones (eight hip joints) performed in an operating room comparing a previously developed optical navigation system with our inertial-based navigation system showed no statistically significant difference on the measurement of acetabular component reorientation. In all eight hip joints the mean absolute difference was below four degrees.
  
  
  CONCLUSIONS
  Using two commercially available inertial measurement units we show that it is possible to accurately measure the orientation (inclination and anteversion) of the acetabular fragment during PAO surgery and therefore to successfully eliminate the line-of-sight impediment that optical navigation systems have.
authors.affiliation: Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland. silvio.pflugi@istb.unibe.ch.
authors.forename: Silvio
authors.initials: S
authors.lastname: Pflugi
authors.affiliation: Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland. li.liu@istb.unibe.ch.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Orthopedic Surgery, Inselspital, University of Bern, Bern, Switzerland. TimoMichael.Ecker@insel.ch.
authors.forename: Timo M
authors.initials: TM
authors.lastname: Ecker
authors.affiliation: Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland. steffen.schumann@istb.unibe.ch.
authors.forename: Steffen
authors.initials: S
authors.lastname: Schumann
authors.affiliation: Department of Radiology, Inselspital, University of Bern, Bern, Switzerland. jennifer.cullmann@insel.ch.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Larissa Cullmann
authors.affiliation: Department of Orthopedic Surgery, Inselspital, University of Bern, Bern, Switzerland. klaus.siebenrock@insel.ch.
authors.forename: Klaus
authors.initials: K
authors.lastname: Siebenrock
authors.affiliation: Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland. guoyan.zheng@istb.unibe.ch.
authors.forename: Guoyan
authors.initials: G
authors.lastname: Zheng
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip / Q000191:economics* / Q000379:methods; D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D010027:Osteotomy / Q000191:economics* / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000191:economics* / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Computer-assisted surgery; Inertial measurement unit; Navigation system; PAO surgery