title: Assessment of pedicle screw placement accuracy, procedure time, and radiation exposure using a miniature robotic guidance system.
abstract: METHODS
  Controlled, cadaveric implantation trial.
  
  
  OBJECTIVE
  To evaluate the effect of a robotic guidance system on screw placement accuracy, amount of radiation exposure, and length of procedure time during percutaneous pedicle screw implantation.
  
  
  BACKGROUND
  Pedicle screws are associated with low complication rates, and several computer-assisted image guidance systems exist that facilitate accurate screw placement. However, these systems may represent substantial radiation exposure risk to patients and surgeons.
  
  
  METHODS
  We implanted 234 pedicle screws in 12 cadavers (study group: 15 surgeons, 197 screws, and 10 specimens; control group: 2 surgeons, 37 screws, and 2 specimens). We measured procedure time, fluoroscopy time, and radiation exposure and evaluated screw placement accuracy with computed tomography scans. To evaluate the learning curve, we compared measurements with those of an experienced robotic guidance user through the 2-sample (heteroscedastic), 1-tail t test (P< 0.05).
  
  
  RESULTS
  Relative to control, the study group had fewer screw placement deviations (average, 2.6±0.7 mm vs. 1.1±0.4 mm; P<0.0001), fewer pedicle wall breaches of 4 mm or greater (average, 5.4% vs. 1.5%), lower surgeon radiation exposure (average, 136 mrem vs. 4.2 mrem), lower fluoroscopy time per screw (average, 33.0 s vs. 0.9 s), and shorter procedure time (average, 1.98 h vs. 1.23 h). Use of robotic guidance increased the accuracy of percutaneous pedicle screw placement by 58%, thereby reducing the risk of neurologic injury (as measured by breaches >4 mm), new-user radiation exposure (by 98.2%), and procedure time (by 36%).
  
  
  CONCLUSIONS
  The advantages associated with a robotic guidance system may make the surgeon more at ease about offering minimally invasive or percutaneous surgical options to patients and more comfortable about implementing pedicle-based fixation in general. This advanced technology may also allow inclusion of patients with complicated anatomic deformities, who are often excluded from pedicle screw-based surgery options.
authors: Texas Back Institute, Plano, TX, USA. ehenze1@jhmi.edu
authors: Isador H
authors: IH
authors: Lieberman
authors: Mitchell A
authors: MA
authors: Hardenbrook
authors: Jeffrey C
authors: JC
authors: Wang
authors: Richard D
authors: RD
authors: Guyer