title: Surgical treatment of adult and pediatric C1/C2 subluxation with intraoperative computed tomography guidance.
abstract: BACKGROUND
  Surgical treatment of C1/C2 subluxation has evolved significantly over the past 2 decades, from the relatively simpler posterior wiring to more technically demanding instrumentations such as C1 lateral mass screws - C2 pedicle screws, C1/C2 transarticular screws, and occipital cervical fusion. Navigation with fluoroscopy is currently the standard of practice in most centers. However, fluoroscopy at this level carries several major drawbacks, such as blockage by the mandible and inability to produce axial images for assessment of the reduction of rotatory subluxation.
  
  
  METHODS
  The authors report a series of 21 patients with C1/C2 subluxation treated surgically with intraoperative computed tomography (ICT) guidance.
  
  
  RESULTS
  There were 7 children and 14 adults. Eight patients underwent C1/C2 fixation with a Harm's construct, and 13 patients underwent occipital cervical fusion. One out of 17 (6%) C1 lateral mass screws has breached the medial wall of lateral mass by 1 mm. Two out of 20 (10%) C2 pedicle screws have breached the foramen transversarium by 1 mm (Neo classification grade 1). The position of all subaxial screws (49 lateral mass screws and 13 pedicle screws) and occipital screws (50 screws) appeared satisfactory. No neurovascular damage occurred in all the patients.
  
  
  CONCLUSIONS
  Ninety eight percent of the screws were placed in ideal position with the aid of ICT. Only 2% of the screws deviated from the planned position, but the breaches were not clinically significant and hence no revision was required. This showed that ICT guidance can help to achieve a high accuracy of surgical instrumentation for the treatment of C1/C2 subluxation.
authors: Department of Neurosurgery, National Neuroscience Institute of Singapore, 11 Jalan Tan Tock Seng, 308433, Singapore.
authors: Ji Min
authors: JM
authors: Ling
authors: Rajendra
authors: R
authors: Tiruchelvarayan
authors: Wan T
authors: WT
authors: Seow
authors: Hua Bi
authors: HB
authors: Ng
keywords: Atlanto-axial subluxation; C1/C2; intraoperative computed tomography; navigation; stereotaxy
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