title: Clinical application of computer-aided design-rapid prototyping in C1-C2 operation techniques for complex atlantoaxial instability.
abstract: METHODS
  This is a retrospective clinical study.
  
  
  OBJECTIVE
  To evaluate the clinical efficacy of computer-aided design-rapid prototyping (CAD-RP) techniques in surgical treatments for atlantoaxial instability (AAI).
  
  
  BACKGROUND
  The complexity of the upper cervical anatomic structures makes the procedures for the treatment of AAI particularly challenging for surgeons. The present study represents a series of C1-C2 surgery for AAI aided by CAD-RP.
  
  
  METHODS
  A total of 49 patients (21 men and 28 women) with AAI were treated in our department. According to the use of the CAD-RP technique, the patients were divided into RP group and No RP group. Preoperative CT scans of the upper cervical spine were performed for each patient. For the RP group, physical RP models of the upper cervical spine were manufactured from the 3-dimensional CT data and were used for intraoperative guidance. Personalized surgeries were performed for each case of the 2 groups. The screw malposition rate, frequency of using intraoperative fluoroscopy, operation time, blood loss, and improvement of neurological function were compared between the 2 groups. The mean follow-up duration was 32 months (range, 24-50 mo).
  
  
  RESULTS
  The operations were successfully performed in 48 cases expect for 1 case in the No RP group. A total of 204 screws were placed. The intraoperative fluoroscopy frequency and operation time were significantly lower in the RP group than that in the No RP group in both posterior and anterior approaches, whereas the screw malposition rate showed no difference between the 2 groups for both approaches. After the operation, 48 cases achieved satisfactory decompression of the cervical cord and repositioning of the atlantoaxial spine. During follow-up, 47 cases presented improvements in the spinal nerve function within 2 years.
  
  
  CONCLUSIONS
  CAD-RP techniques have significant benefits for surgeons providing personalized treatments for AAI, especially cases with complicated deformities.
authors.affiliation: Department of Orthopedics, General Hospital of Guangzhou Military Command of PLA, Guangzhou, People's Republic of China.
authors.forename: Jin-Cheng
authors.initials: JC
authors.lastname: Yang
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Ma
authors.forename: Hong
authors.initials: H
authors.lastname: Xia
authors.forename: Zeng-Hui
authors.initials: ZH
authors.lastname: Wu
authors.forename: Fu-Zhi
authors.initials: FZ
authors.lastname: Ai
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Qing-Shui
authors.initials: QS
authors.lastname: Yin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D017076:Computer-Aided Design; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods; D014057:Tomography, X-Ray Computed; D055815:Young Adult