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Minimally invasive percutaneous transpedicular screw fixation: increased accuracy and reduced radiation exposure by means of a novel electromagnetic navigation system.

von Jako R, Finn MA, Yonemura KS, Araghi A, Khoo LT, Carrino JA, Perez-Cruet M - Acta Neurochir (Wien) (2010)

Bottom Line: Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p = 0.03, and 16.2% vs. 42.5%, p = 0.01, respectively).Time for insertion did not vary between the two techniques.Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.

View Article: PubMed Central - PubMed

Affiliation: GE Healthcare, Boston, MA, USA. drvonjako@comcast.net

ABSTRACT

Background: Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement.

Methods: Minimally invasive pedicle screw placement in T8 to S1 pedicles of eight fresh-frozen human cadaveric torsos was guided with EMF or standard fluoroscopy. Set-up, insertion, and fluoroscopic times and radiation exposure and accuracy (measured with post-procedural computed tomography) were analyzed in each group.

Results: Sixty-two pedicle screws were placed under fluoroscopic guidance and 60 under EMF guidance. Ideal trajectories were achieved more frequently with EMF over all segments (62.7% vs. 40%; p = 0.01). Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p = 0.03, and 16.2% vs. 42.5%, p = 0.01, respectively). Fluoroscopy time was reduced 77% with the use of EMF (22 s vs. 5 s per level; p < 0.0001) over all spinal segments. Radiation exposure at the hand and body was reduced 60% (p = 0.058) and 32% (p = 0.073), respectively. Time for insertion did not vary between the two techniques.

Conclusions: Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.

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Related in: MedlinePlus

Photograph showing the GE OEC 9900 Elite fluoroscopic display
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Fig2: Photograph showing the GE OEC 9900 Elite fluoroscopic display

Mentions: A GE OEC 9900 Elite fluoroscope with an integrated navigation system (GE Healthcare, Salt Lake City, UT; not commercially available) was used for fluoroscopic imaging (Fig. 2). To eliminate bias and confirm that the navigation system works with multiple screw constructs, two minimally invasive percutaneous pedicle screw systems that had been modified for use in an EMF environment were used: the Paramount (Integra Spine, Burlington, MA, USA) and the Pathfinder (Zimmer Spine, Austin, TX, USA) systems. Titanium screw extenders for each system were created to avoid interference within the EMF field that would be expected from the normal stainless steel extenders. A special bone biopsy needle known as the Nav Access Needle [33], which provides stable attachment of an EMF receiver, was used for Kirschner wire (K-wire) placement. A bone pin or spinous process clamp was used to attach the EMF dynamic reference transmitter to the spinous process of the level adjacent to the targeted vertebrae as previously described (Fig. 3) [11, 35]. The typical montage for transmitter placement was on the spinous processes of T11, L2, and L5, as the system allows for accurate navigation of up to three vertebrae from each transmitter location. For two cadavers, T8 was also used for placement of the EMF transmitter.Fig. 2


Minimally invasive percutaneous transpedicular screw fixation: increased accuracy and reduced radiation exposure by means of a novel electromagnetic navigation system.

von Jako R, Finn MA, Yonemura KS, Araghi A, Khoo LT, Carrino JA, Perez-Cruet M - Acta Neurochir (Wien) (2010)

Photograph showing the GE OEC 9900 Elite fluoroscopic display
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040822&req=5

Fig2: Photograph showing the GE OEC 9900 Elite fluoroscopic display
Mentions: A GE OEC 9900 Elite fluoroscope with an integrated navigation system (GE Healthcare, Salt Lake City, UT; not commercially available) was used for fluoroscopic imaging (Fig. 2). To eliminate bias and confirm that the navigation system works with multiple screw constructs, two minimally invasive percutaneous pedicle screw systems that had been modified for use in an EMF environment were used: the Paramount (Integra Spine, Burlington, MA, USA) and the Pathfinder (Zimmer Spine, Austin, TX, USA) systems. Titanium screw extenders for each system were created to avoid interference within the EMF field that would be expected from the normal stainless steel extenders. A special bone biopsy needle known as the Nav Access Needle [33], which provides stable attachment of an EMF receiver, was used for Kirschner wire (K-wire) placement. A bone pin or spinous process clamp was used to attach the EMF dynamic reference transmitter to the spinous process of the level adjacent to the targeted vertebrae as previously described (Fig. 3) [11, 35]. The typical montage for transmitter placement was on the spinous processes of T11, L2, and L5, as the system allows for accurate navigation of up to three vertebrae from each transmitter location. For two cadavers, T8 was also used for placement of the EMF transmitter.Fig. 2

Bottom Line: Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p = 0.03, and 16.2% vs. 42.5%, p = 0.01, respectively).Time for insertion did not vary between the two techniques.Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.

View Article: PubMed Central - PubMed

Affiliation: GE Healthcare, Boston, MA, USA. drvonjako@comcast.net

ABSTRACT

Background: Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement.

Methods: Minimally invasive pedicle screw placement in T8 to S1 pedicles of eight fresh-frozen human cadaveric torsos was guided with EMF or standard fluoroscopy. Set-up, insertion, and fluoroscopic times and radiation exposure and accuracy (measured with post-procedural computed tomography) were analyzed in each group.

Results: Sixty-two pedicle screws were placed under fluoroscopic guidance and 60 under EMF guidance. Ideal trajectories were achieved more frequently with EMF over all segments (62.7% vs. 40%; p = 0.01). Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p = 0.03, and 16.2% vs. 42.5%, p = 0.01, respectively). Fluoroscopy time was reduced 77% with the use of EMF (22 s vs. 5 s per level; p < 0.0001) over all spinal segments. Radiation exposure at the hand and body was reduced 60% (p = 0.058) and 32% (p = 0.073), respectively. Time for insertion did not vary between the two techniques.

Conclusions: Minimally invasive pedicle screw placement with the aid of EMF image guidance reduces fluoroscopy time and increases placement accuracy when compared with traditional fluoroscopic guidance while adding no additional time to the procedure.

Show MeSH
Related in: MedlinePlus