Role of intraoperative Iso-C based navigation in challenging spine trauma

Abstract

Background: Pedicle screw fixation is the most preferred method of stabilizing unstable spinal fractures. Pedicle screw placement may be difficult in presence of fractured posterior elements, deformed spine, gross instability and spinal pathology. Challenging spine-fracture fixation is defined as the presence of one or more of the following: 1) obscured topographical landmarks as in ankylosing spondylitis, 2) fractures in occipitocervical or cervicothoracic regions and 3) preexisting altered spinal alignment. We report a series of pedicle screw insertion with guidance of navigation in difficult fixation problems..

Materials and methods: Fourteen patients [hangman's fracture (n=3), odontoid fracture (n=4), C1C2 fracture (n=1) and spinal fracture with coexistent ankylosing spondylitis (n=6)] underwent posterior stabilization. Intraoperatively after surgical exposure, images were acquired by Iso-C 3D C-arm and transferred to navigation system. Instrumentation was performed with navigational assistance. Postoperatively, placements of pedicle screws were evaluated with radiographs and CT scan.

Results: Sixty-seven pedicle screws (cervical, n=33; thoracic, n=6; lumbar, n=26; sacral n=2) and 15 lateral mass screws were inserted with navigation guidance. The average time of image data acquisition by Iso-C 3D C-arm and its transfer to workstation was 4 minutes (range, 2-6 minutes). Postoperative CT scan revealed ideal placement of screws in 63 pedicles (94%), grade 1 cortical breaches (<2 mm) in 3 pedicles (4.5%) and grade 2 cortical breach (2-4 mm) in one pedicle (1.5%). There were no neurovascular complications. Deep infection was encountered in one case, which settled with debridement.

Conclusions: Intraoperative Iso-C 3D C-arm based navigation is a useful adjunct while stabilizing challenging spinal trauma, rendering feasibility, accuracy and safety of pedicle screw placement even in difficult situations.

Keywords: Computer-assisted surgery; challenging spinal trauma; neuronavigation; pedicle screw; spine fracture.

Figure 1

A 58-year-old female (case 2) with nonunion fracture odontoid with atlantoaxial instability (a,b,c). Preoperative halo-vest traction (d) was given. Posterior instrumented C1C2 fusion was planned. Intraoperative navigation (e,f) helped in accurate localization of entry point and in ascertaining trajectory and dimensions of pedicle screws. Postoperative radiographs (g,h) showed satisfactory alignment. Ten-month follow-up CT scan (i,j) showed good placement of C1 and C2 pedicle screw and union in satisfactory alignment (k,l).

Figure 2

A 58-year-old male (case 12) with ankylosing spondylitis sustained chance fracture at C3-C4 (a,b,c) with ASIA grade B neurological deficit. Posterior instrumented fusion and decompression was planned. Intraoperative navigation pictures (d,e) showing multiplanar pedicle entry point and trajectory localization. Intraoperative photograph (f) and postoperative radiographs showing good placement of pedicle and lateral mass screws (g,h)