title: Navigated pelvic osteotomy and tumor resection: a study assessing the accuracy and reproducibility of resection planes in Sawbones and cadavers.
abstract: BACKGROUND
  This Sawbones and cadaver study was performed to assess the accuracy and reproducibility of pelvic bone cuts made with use of a novel navigation system with a navigated osteotome and oscillating saw.
  
  
  METHODS
  Using a novel navigation system and a three-dimensional planning tool, we navigated pelvic bone cuts that were representative of typical cuts made in pelvic tumor resections. The system includes a prototype mobile C-arm for intraoperative cone-beam computed tomography, real-time optical tracking (Polaris), and three-dimensional visualization software. Three-dimensional virtual radiographs were utilized in addition to triplanar (axial, sagittal, and coronal) navigation. In part one of the study, we navigated twenty-four sacral bone cuts in Sawbones models and validated our results in sixteen similar cuts in cadavers. In part two, we developed three Sawbones models of pelvic tumors based on actual patient scenarios and compared three navigated resections with three non-navigated resections for each tumor model. Part three assessed the accuracy of the system with multiple users.
  
  
  RESULTS
  There were ninety navigated cuts in Sawbones that were compared with fifty-four non-navigated cuts. In the navigated Sawbones cuts, the mean entry and exit cuts were 1.4 ± 1 mm and 1.9 ± 1.2 mm from the planned cuts, respectively. In comparison, the entry and exit cuts in Sawbones that were not navigated were 2.8 ± 4.9 mm and 3.5 ± 4.6 mm away from the planned osteotomy site. The navigated cuts were significantly more accurate (p ≤ 0.01). In the cadaver study, navigated entry and exit cuts were 1.5 ± 0.9 mm and 2.1 ± 1.5 mm from the planned cuts. The variation among three different users was 1 mm on both the entry and exit cuts.
  
  
  CONCLUSIONS
  Navigation to guide pelvic bone cuts is accurate and feasible. Three-dimensional radiographs should be used for improved accuracy. Navigated cuts were significantly more accurate than non-navigated cuts were. A margin of 5 mm between the target tumor volume and the planned cut plane would result in a negative margin resection in more than 95% of the cuts.
  
  
  CONCLUSIONS
  The accuracy of pelvic bone tumor resections and pelvic osteotomies can be improved with navigation to within 5 mm of the planned cut.
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, 600 University Avenue, Room 476, Toronto, ON M5G 1X5, Canada. E-mail address for A. Sternheim: amirsternheim@gmail.com. E-mail address for J.S. Wunder: jwunder@mtsinai.on.ca.
authors.forename: Amir
authors.initials: A
authors.lastname: Sternheim
authors.affiliation: GTx Core-Techna Institute, University Health Network, 101 College Street, 7-1001, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada. E-mail address for M. Daly: michael.daly@rmp.uhn.on.ca. E-mail address for J. Qiu: jimmy.qiu@rmp.uhn.on.ca. E-mail address for R. Weersink: robert.weersink@rmp.uhn.on.ca. E-mail address for H. Chan: harley.chan@rmp.uhn.on.ca.
authors.forename: Michael
authors.initials: M
authors.lastname: Daly
authors.affiliation: GTx Core-Techna Institute, University Health Network, 101 College Street, 7-1001, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada. E-mail address for M. Daly: michael.daly@rmp.uhn.on.ca. E-mail address for J. Qiu: jimmy.qiu@rmp.uhn.on.ca. E-mail address for R. Weersink: robert.weersink@rmp.uhn.on.ca. E-mail address for H. Chan: harley.chan@rmp.uhn.on.ca.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Qiu
authors.affiliation: GTx Core-Techna Institute, University Health Network, 101 College Street, 7-1001, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada. E-mail address for M. Daly: michael.daly@rmp.uhn.on.ca. E-mail address for J. Qiu: jimmy.qiu@rmp.uhn.on.ca. E-mail address for R. Weersink: robert.weersink@rmp.uhn.on.ca. E-mail address for H. Chan: harley.chan@rmp.uhn.on.ca.
authors.forename: Robert
authors.initials: R
authors.lastname: Weersink
authors.affiliation: GTx Core-Techna Institute, University Health Network, 101 College Street, 7-1001, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada. E-mail address for M. Daly: michael.daly@rmp.uhn.on.ca. E-mail address for J. Qiu: jimmy.qiu@rmp.uhn.on.ca. E-mail address for R. Weersink: robert.weersink@rmp.uhn.on.ca. E-mail address for H. Chan: harley.chan@rmp.uhn.on.ca.
authors.forename: Harley
authors.initials: H
authors.lastname: Chan
authors.affiliation: Ontario Cancer Institute, 610 University Avenue, 5-631, Toronto, ON M5G 1X5, Canada. E-mail address: david.jaffray@rmp.uhn.ca.
authors.forename: David
authors.initials: D
authors.lastname: Jaffray
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Princess Margaret Cancer Centre, 610 University Avenue, 3-954, Toronto, ON M5G 2M9, Canada. E-mail address: jonathan.irish@uhn.ca.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Irish
authors.affiliation: Department of Surgery, Mount Sinai Hospital, 600 University Avenue, Suite 476G, Toronto, ON M5G 1X5, Canada. E-mail address: pferguson@mtsinai.on.ca.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Ferguson
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, 600 University Avenue, Room 476, Toronto, ON M5G 1X5, Canada. E-mail address for A. Sternheim: amirsternheim@gmail.com. E-mail address for J.S. Wunder: jwunder@mtsinai.on.ca.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Wunder
mesh_terms: D001859:Bone Neoplasms / Q000601:surgery*; D002102:Cadaver; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008953:Models, Anatomic; D010027:Osteotomy / Q000295:instrumentation / Q000379:methods*; D010384:Pelvic Bones / Q000601:surgery*; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed