Comparison of Open and Percutaneous Lumbar Pedicle Screw Revision Rate Using 3-Dimensional Image Guidance and Intra-Operative Computed Tomography

Presented at SMISS Annual Forum 2013
By Sharon C. Yson MD
With Jonathan N. Sembrano MD, Edward G. Santos MD, David W. Polly, Jr. MD,

Disclosures: Sharon Yson MD Jonathan Sembrano MD A; NuVasive, Inc - PI for an RCT comparing MAS-TLIF vs XLIF, SI Bone Inc., Edward Santos MD A; SI Bone, Inc - PI for RCT., David Polly, Jr. MD A; DOD, SRS, POSNA. E; University of Minnesota.,

Introduction: Complications arising from malpositioned screw can both be devastating and costly. The incidence of neurologic injury secondary to malpositioned screw is reported to be as high as 7-12%. The advancement of image-guidance technology has allowed for more precise pedicle screw insertion. Moreover, the availability of intra-operative computed tomography (CT) permitted surgeons to confirm correct screw placement prior to leaving the operating room. The accuracy of navigated pedicle screw placement, in terms of pedicle perforation, has been well reported in literature. A small number of studies examined image-guided pedicle screw accuracy in terms of intra-operative revision and re-operation rates.

Purpose: The aims of this study are to determine intraoperative screw revision and re-operation rates of lumbar pedicle screw inserted with 3-D CT navigation and to compare navigated open and percutaneous techniques.
Methods: We reviewed 199 cases of 3D image-guided lumbar pedicle screw instrumentation from Nov 2006 to Dec 2011. Screw or k-wire removal, repositioning or eventual abandonment of insertion based of intra-operative confirmatory scans were noted. Chi-square was used to determine statistical significance in rates between the two groups (a=0.05). We also noted for any return to surgery secondary to complications from malpositioned screw.

Results: A total of 988 screws (601 open, 387 percutaneous) were reviewed. Forty-five screws and/or k-wire evisions (4.6%) were done overall; 16 screws (2.7%) were revised in the open group; 21 k-wires (5.4%) and 8 screws (2.1%) were revised in the percutaneous group (Table). There were no neurovascular complications secondary to screw position that was noted during the immediate post-operative period. No patient needed return to surgery for revision of malpositioned screw.
The difference in the revision rates between the open and percutaneous group was statistically significant (p=0.0004). However, if k-wire revision was excluded and only screw revision was taken into account, the difference was not statistically significant (p=0.55).

Conclusion: We report a 4.6% intra-operative revision rate with the use of navigation and intra-operative CT scan. This technology has virtually eliminated the need for a re-operation secondary to a malpositioned screw. It may suggest a more cost-effective way of preventing neurovascular injuries and revision surgery. However, taking into account the potential for increased radiation to patient, more dedicated studies on this new technology’s impact on health economics should be undertaken.