title: Accuracy and safety assessment of pedicle screw placement using the rapid prototyping technique in severe congenital scoliosis.
abstract: METHODS
  The application of rapid prototyping (RP) technique for improving accuracy of pedicle screw placement in congenital scoliosis is described in this study.
  
  
  OBJECTIVE
  To compare the accuracy and safety of pedicle screw placement in congenital scoliosis using the RP technique versus the conventional fluoroscopy.
  
  
  BACKGROUND
  Maldeveloped vertebral components in congenital scoliosis leads to prolonged operation time and higher rate of screw misplacement. RP technique can enhance preoperative and perioperative planning. No data are available on the accuracy of pedicle screw fixation using the RP technique.
  
  
  METHODS
  Sixty-two consecutive patients with hemivertebra had undergone posterior-only hemivertebra resection. Pedicle screws were implanted either by the conventional intraoperative fluoroscopy technique (C-arm group; n=28) or the RP technique (RP group; n=34). Accuracy of pedicle screw placement was compared by postoperative computed tomographic scan.
  
  
  RESULTS
  Seventy of 677 inserted screws were found to be misplaced, showing an overall accuracy of 89.7% (90.8% in the thoracic spine and 87.4% in the lumbar spine). In the C-arm group, 86.1% (167 of 194) and 82.0% (82 of 100) of screws were accurately placed in the thoracic and lumbar spine, respectively. While in the RP group, the respective screw placement accuracies were 94.4% (238 of 252) and 91.6% (120 of 131). In the C-arm and the RP groups, 94.8% (279 of 294) and 97.9% (375 of 383) of the screws were within the safety zone, respectively. Compared with the fluoroscopy method, the RP-assisted technique showed a shorter operation time and higher scoliosis correction rate. No neurovascular-related complication was observed with this technique during the study.
  
  
  CONCLUSIONS
  The application of RP technique in congenital scoliosis can reduce the operation time, the risk of screw misplacement and its consequent complications. The use of RP technique in congenital scoliosis is safe and efficacious.
authors.affiliation: Institude of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, Xi'an, Shaanxi Province, PR China.
authors.forename: Zi-Xiang
authors.initials: ZX
authors.lastname: Wu
authors.forename: Lu-Yu
authors.initials: LY
authors.lastname: Huang
authors.forename: Hong-Xun
authors.initials: HX
authors.lastname: Sang
authors.forename: Zhen-Sheng
authors.initials: ZS
authors.lastname: Ma
authors.forename: Shi-Yong
authors.initials: SY
authors.lastname: Wan
authors.forename: Geng
authors.initials: G
authors.lastname: Cui
authors.forename: Wei
authors.initials: W
authors.lastname: Lei
mesh_terms: D000293:Adolescent; D001863:Bone Screws / Q000592:standards*; D002648:Child; D002675:Child, Preschool; D005500:Follow-Up Studies; D006801:Humans; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D011300:Preoperative Care / Q000379:methods / Q000592:standards*; D012600:Scoliosis / Q000151:congenital / Q000000981:diagnostic imaging / Q000601:surgery*; D012720:Severity of Illness Index; D013123:Spinal Fusion / Q000379:methods / Q000592:standards*; D014057:Tomography, X-Ray Computed; D055815:Young Adult