Study Design. Retrospective study comparing cranial facet joint violation rates of open and percutaneous pedicle screws inserted using 3-dimensional image-guidance.
Objective. To determine the rate of cranial facet joint violation in intraoperative computed tomography (CT) image-guided lumbar pedicle screw instrumentation and compare facet joint violation rates between CT image-guided open and percutaneous techniques.
Summary of Background Data. Facet joint violation by pedicle screws can potentially result in a higher rate of adjacent segment degeneration. Reported cranial facet joint violation rates range from 7% to 100%. Intraoperative image-guidance, which has enhanced pedicle screw placement accuracy, may aid in avoiding impingement of the cranial facet joints.
Methods. We reviewed 188 cases of 3-dimensional image-guided lumbar pedicle screw instrumentation from November 2006 to December 2011. The cranial screws of each construct were graded by 3 reviewers according to the Seo classification (0 = no impingement; 1 = screw head in contact/suspected to be in contact with joint; 2 = screw clearly invaded the joint) on intraoperative axial CT images. If there was a difference in evaluation, a consensus was reached to arrive at a single grade. The χ2 test was used to determine significance between the open and percutaneous group (α = 0.05).
Results. A total of 370 screws (245 open, 125 percutaneous) were graded. Overall facet joint violation rate was 18.9% (grade 1 = 16.2%, grade 2 = 2.7%). Open technique (grade 1 = 22.4%, grade 2 = 4.1%) had a significantly higher violation rate than percutaneous technique (grade 1 = 4%, grade 2 = 0%) (P < 0.0001). There is a trend of an increasing likelihood of facet joint violation from L1 to L5.
Conclusion. The use of intraoperative CT image-guidance in lumbar pedicle screw placement resulted in a facet joint violation rate at the lower end of the reported range in literature. The percutaneous technique has a significantly lower facet violation rate than the open technique.
Level of Evidence: 4
In a review of 188 cases of 3-dimensional image-guided lumbar pedicle screw insertion, we report a cranial facet joint violation rate of 19%. Percutaneous technique has a significantly lower violation rate than open technique (4% vs. 24%, P < 0.0001). Likelihood of facet joint violation increases from L1 to L5.
*Department of Orthopaedic Surgery
†Department of Neurosurgery University of Minnesota, Minneapolis, MN
Address correspondence and reprint requests to Jonathan N. Sembrano, MD, 2450 Riverside Ave South, Ste R200, Minneapolis, MN 55454; E-mail: firstname.lastname@example.org
Acknowledgment date: July 26, 2012. Revision date: October 1, 2012. Acceptance date: November 14, 2012.
The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.
No funds were received in support of this work.
Relevant financial activities outside the submitted work: grants, consultancy, payment for lecture.