Elsevier

World Neurosurgery

Volume 125, May 2019, Pages e863-e872
World Neurosurgery

Original Article
Optical Topographic Imaging for Spinal Intraoperative Three-Dimensional Navigation in Mini-Open Approaches: A Prospective Cohort Study of Initial Preclinical and Clinical Feasibility

https://doi.org/10.1016/j.wneu.2019.01.201Get rights and content

Objective

Computer-assisted three-dimensional navigation often guides spinal instrumentation. Optical topographic imaging (OTI) offers comparable accuracy and significantly faster registration relative to current navigation systems in open posterior thoracolumbar exposures. We validate the usefulness and accuracy of OTI in minimally invasive spinal approaches.

Methods

Mini-open midline posterior exposures were performed in 4 human cadavers. Square exposures of 25, 30, 35, and 40 mm were registered to preoperative computed tomography imaging. Screw tracts were fashioned using a tracked awl and probe with instrumentation placed. Navigation data were compared with screw positions on postoperative computed tomography imaging, and absolute translational and angular deviations were computed.

In vivo validation was performed in 8 patients, with mini-open thoracolumbar exposures and percutaneous placement of navigated instrumentation. Navigated instrumentation was performed in the previously described manner.

Results

For 37 cadaveric screws, absolute translational errors were (1.79 ± 1.43 mm) and (1.81 ± 1.51 mm) in the axial and sagittal planes, respectively. Absolute angular deviations were (3.81 ± 2.91°) and (3.45 ± 2.82°), respectively (mean ± standard deviation). The number of surface points registered by the navigation system, but not exposure size, correlated positively with the likelihood of successful registration (odds ratio, 1.02; 95% confidence interval, 1.009–1.024; P < 0.001).

Fifty-five in vivo thoracolumbar pedicle screws were analyzed. Overall (mean ± standard deviation) axial and sagittal translational errors were (1.79 ± 1.41 mm) and (2.68 ± 2.26 mm), respectively. Axial and sagittal angular errors were (3.63° ± 2.92°) and (4.65° ± 3.36°), respectively. There were no radiographic breaches >2 mm or any neurovascular complications.

Conclusions

OTI is a novel navigation technique previously validated for open posterior exposures and in this study has comparable accuracy for mini-open minimally invasive surgery exposures. The likelihood of successful registration is affected more by the geometry of the exposure than by its size.

Introduction

Intraoperative three-dimensional (3D) computer-assisted navigation (CAN) has become standard of care in cranial neurosurgery for the localization of subsurface anatomy. Spinal CAN often guides instrumentation placement and tissue resection; however, adoption has been limited by cumbersome and lengthy registration protocols, workflow hindrances, steep learning curves, and high costs.1, 2, 3, 4, 5, 6

The usefulness of CAN is most apparent in minimally invasive surgery (MIS) and deformity-correcting procedures, in which anatomic landmarks are not directly visible or are significantly distorted.1, 5, 7, 8 MIS techniques, through mini-open, tubular, and/or endoscopic approaches, have been shown to shorten hospital length of stay, minimize intraoperative blood loss, and improve short-term patient-reported outcomes. The impact on operative time and postoperative complications, relative to comparable open spinal procedures, remains to be defined.9, 10, 11, 12, 13, 14 However, MIS approaches have typically been guided by intraoperative fluoroscopy or computed tomography (CT). These techniques are associated with substantial radiation exposure and workflow disruption.15

Optical topographic imaging (OTI) is a novel technique for 3D surface acquisition, patient-to-image registration, and intraoperative navigation, developed by our research group. OTI registers significantly faster than CAN systems with comparable accuracy and without intraoperative radiation exposure.16 This technology obviates many of the limitations of CAN techniques.1, 5 In its current iteration, OTI requires line of sight to exposed bony anatomy to allow machine-vision cameras to generate a virtual 3D surface for patient-to-image registration. OTI has been validated only in open posterior thoracolumbar approaches with incisions exposing >3 spinal levels.

In this study, we assess the ability of OTI to perform successful patient-to-image registration and accurate intraoperative navigation in mini-open spinal procedures. We explore predictors of successful registration and their correlation with quantitative navigation accuracy.

Section snippets

Methods

Reporting of all methodology is performed in accordance with the criteria for STROBE (Strengthening the Reporting of Observational Studies in Epidemiology [www.strobe-statement.org]).

Results

For the 4 cadavers used in preclinical validation, mean age at death was 91.4 years (range, 83–96 years). Thirty-seven screws from the 4 cadavers were included in our analysis: 8 pedicle screws at T2, 10 at T6, 9 at T10, and 4 pedicle and 6 cortical screws at L3. One pedicle at T10 was not analyzed because of the unavailability of appropriate instrumentation to place at this level.

In vivo clinical feasibility was assessed in 8 patients, with mean age 57.2 years. Fifty-five thoracolumbar pedicle

Discussion

The primary purported benefit of CAN for spinal procedures is improved instrumentation accuracy and, in theory, minimization of acute and long-term complications from misplaced screws. CAN has been shown to reduce pedicle screw breach rates from 12%–40% with freehand or fluoroscopic guidance to <5% with 3D CAN.23, 24, 25, 26, 27, 28 Improved instrumentation accuracy is seen across all 3D CAN techniques, registering to preoperative or intraoperative imaging, in each of the cervical, thoracic,

Conclusions

Optical machine vision is a novel navigation technique previously validated for open posterior exposures. OTI is feasible for mini-open MIS exposures in preclinical and initial clinical testing, with comparable radiographic accuracy to that achieved by OTI in open exposures. The likelihood of successful registration depends on the number of points acquired and registered by the navigation system but not exposure size. With the exception of sagittal angular deviation, absolute navigation

Acknowledgments

This research is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI). Salary support for D.G. was provided in part by a Canadian Institutes of Health Research (CIHR) postdoctoral fellowship (FRN 142931).

References (41)

  • N. Hecht et al.

    Accuracy and workflow of navigated spinal instrumentation with the mobile AIRO(®) CT scanner

    Eur Spine J

    (2016)
  • S. Bandiera et al.

    Navigation-assisted surgery for tumors of the spine

    Eur Spine J

    (2013)
  • Y. Sakai et al.

    Segmental pedicle screwing for idiopathic scoliosis using computer-assisted surgery

    J Spinal Disord Tech

    (2008)
  • L. Al-Khouja et al.

    Economics of image guidance and navigation in spine surgery

    Surg Neurol Int

    (2015)
  • W. Hu et al.

    Minimally invasive versus open transforaminal lumbar fusion: a systematic review of complications

    Int Orthop

    (2016)
  • S. McAnany et al.

    Open versus minimally invasive fixation techniques for thoracolumbar trauma: a meta-analysis

    Glob Spine J

    (2015)
  • C.L. Goldstein et al.

    Perioperative outcomes and adverse events of minimally invasive versus open posterior lumbar fusion: meta-analysis and systematic review

    J Neurosurg Spine

    (2016)
  • K. Phan et al.

    Minimally invasive versus open laminectomy for lumbar stenosis

    Spine (Phila Pa 1976)

    (2016)
  • F. Costa et al.

    Radiation exposure in spine surgery using an image-guided system based on intraoperative cone-beam computed tomography: analysis of 107 consecutive cases

    J Neurosurg Spine

    (2016)
  • R. Jakubovic et al.

    High speed, high density intraoperative 3D optical topographical imaging with efficient registration to MRI and CT for craniospinal surgical navigation

    Sci Rep

    (2018)
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    Conflict of interest statement: V.X.D.Y. is co-founder and Chief Scientific Officer of 7D Surgical Inc., a company licensing the OTI technology described in this article. There are no material or financial conflicts of interest arising from this study. The remaining authors have no relevant conflicts of interest to disclose. This research is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI). Salary support for D.G. was provided in part by a Canadian Institutes of Health Research (CIHR) postdoctoral fellowship (FRN 142931).

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