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DOI: 10.1055/s-0034-1383811
Systematic Use of Intraoperative Cone Beam-Computed Tomography with Navigation (O-arm) in Screw Positioning: Review of a 1-Year Single Center Experience
Aims: The main aim of this retrospective analysis was to examine the real impact of the systematic use of a cone beam computed tomography with navigation (O-arm) on screw positioning in spine arthrodesis procedures.
Our initial hypothesis was that using this technique in a standardized and systematic way, we could reduce damage to neurovascular structures, augment the precision of screw positioning, and reduce intraoperative time.
Methods: The analysis includes 144 patients submitted to posterior spine arthrodesis with screws, from January 2013 to December 2013. All were operated with aid of Neuronavigation. 75% of the patients had degenerative lesion, while the remaining 25% had traumatic, neoplastic or infectious diseases. In the same period, other patients were submitted to same procedures without the use of O-arm, mainly because this was not available due to the simultaneous use of the machine by orthopedic surgeons.
Preoperative and intraoperative data were retrospectively collected and analyzed in all patients. All patients were postoperatively submitted to CT scans with sagittal and coronal reconstructions, within 24 hours after surgery to assess screw positioning. The position of the screws was analyzed on postoperative CT and the degree of perforation of the cortical bone of the pedicle was classified according to criteria published in other studies1 in 4 grades: Grade 1 (0- 2mm), Grade 2 (2 -4mm), Grade 3 (4 -6mm), Grade 4 (over 6 mm).
Results: Mean age was 66 years old. A total of 868 pedicle screws were placed, between C1 and S1.
11 procedures (7%) were at cervical levels, 21 (14%) at thoracic levels, and 112 (77%) at lumbar levels. No patient presented neurologic complications related to screw malpositioning. On postoperative CT scans, 98% of screws were classified as grade 1, and 2% as grade 2, while no screw was classified as grade 3 or 4. In patients operated without the O-arm precision was less, with a statistically significant difference between the two groups. No difference was noted in surgical time with the O-arm.
Conclusions: Cone beam computed tomography with navigation (O-arm) has become a useful tool in all spine procedures with pedicular screw positioning. The main field of application, i.e., the field in which the technique has the greater clinical impact is posterior thoracic pedicular screw positioning, especially in the T1-T6 district. Other situations are C1-C2 posterior screwing with rotatory subluxation of C1, and lumbar screw positioning in degenerative deformity cases with posterior arthrosis. Systematic use of Navigation has also changed our surgical technique, because now we position all screws before doing any bony decompression, thus reducing blood loss and risk of neurological damage.
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