title: Pedicle screw piercer with warning device - A technique to increase accuracy of pedicle screw placement: A cadaveric study.
abstract: BACKGROUND
  Pedicle screw fixation has achieved significant popularity amongst spinal surgeons for both single and multilevel spinal fusion. Suboptimal placements of pedicle screws may lead to neurological and vascular complications. There have been many advances in techniques available for navigating through the pedicle; however, these techniques are not without drawbacks. The purpose of this study was to investigate the efficacy and feasibility of the pedicle piercer with warning device.
  
  
  METHODS
  Eight normal adult thoracolumbar specimens from cadavers consisting of 80 vertebras (T8-L5) were selected and randomly allocated into four groups. Each group contained 20 vertebra. Group 1 was tested for maximum pressure of the piercer within the vertebrae (F1). Group 2 was tested for maximum pressure of the warning piercer penetrating front cortex of the vertebral body (F2). Group 3 was tested for the maximum pressure of piercer penetrating vertebral body endplate (F3) and pedicle notch (F41, F42). Group 4 was tested for maximum pressure of the piercer penetrating the vertebral lateral cortex (F6), the medial and lateral cortex of pedicle (F51, F52). In the second experiment of this study, 4 normal adult specimens consisting of 40 vertebra and 80 pedicles were used for testing the alarm effects of pedicle piercer. The following indicators were adopted for the tests including true positive/negative, false positive/negative, sensitivity, specificity, availability, Youden index, and diagnostic efficiency. SPSS 16.0 was used for statistical analysis.
  
  
  RESULTS
  There were statistically significant differences between F1, and F2, F3, F41, F42, F51, F52 respectively (P < 0.05). F1 = 8.970 ± 0.2698, F3 = 13.055 ± 0.6718. We found that the threshold value of piercer warning was from 9.6 to 12.3 Kgf. Sensitivity was 92.31%, specificity was 95.12%, usability was 87.45%, Youden index was 87.43% and diagnostic efficiency was 92.5% respectively.
  
  
  CONCLUSIONS
  Warning piercer is a safe, simple, sensitive device for detecting pedicle breach during regular pedicle screw placement surgery.
authors.affiliation: Department of Orthopaedics, The 175 Hospital of PLA, Traumatic Orthopaedics Center of PLA, Southeast Hospital of Xiamen University, Zhangzhou, Fujian Province, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Bin
authors.affiliation: Department of Orthopaedics, The 175 Hospital of PLA, Traumatic Orthopaedics Center of PLA, Southeast Hospital of Xiamen University, Zhangzhou, Fujian Province, PR China.
authors.forename: He
authors.initials: H
authors.lastname: Yong
authors.affiliation: Department of Orthopaedics, The 175 Hospital of PLA, Traumatic Orthopaedics Center of PLA, Southeast Hospital of Xiamen University, Zhangzhou, Fujian Province, PR China.
authors.forename: Xu
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Orthopaedics, The 175 Hospital of PLA, Traumatic Orthopaedics Center of PLA, Southeast Hospital of Xiamen University, Zhangzhou, Fujian Province, PR China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Bi
authors.affiliation: Department of Orthopaedics, The 175 Hospital of PLA, Traumatic Orthopaedics Center of PLA, Southeast Hospital of Xiamen University, Zhangzhou, Fujian Province, PR China.
authors.forename: Sha
authors.initials: S
authors.lastname: Mo
authors.affiliation: Department of Orthopaedics, The 175 Hospital of PLA, Traumatic Orthopaedics Center of PLA, Southeast Hospital of Xiamen University, Zhangzhou, Fujian Province, PR China.
authors.forename: Guo
authors.initials: G
authors.lastname: Zhi-Min
keywords: Pedicle screw piercer; Spine; bone screws; cadaver; cadaveric study; lumbar region; thoracic injuries; thoracolumbar specimens; warning device