Lumbar spine superior-level facet joint violations: percutaneous versus open pedicle screw insertion using intraoperative 3-dimensional computer-assisted navigation.

Background: Percutaneous pedicle screw use has a high rate of cranial facet joint violations (FVs) because of the facet joint being indirectly visualized. Computer-assisted navigation shows the anatomic structures clearly, and may help to lower the rate of FVs during pedicle screw insertion. This study used computed tomography (CT) to evaluate and compare the incidence of FVs between percutaneous and open surgeries employing computer-assisted navigation for the implantation of pedicle screw instrumentation during lumbar fusions.

Methods: A prospective study, including 142 patients having lumbar and lumbosacral fusion, was conducted between January 2013 and April 2014. All patients had bilateral posterior pedicle screw-rod instrumentation (top-loading screws) implanted by the same group of surgeons; intraoperative 3-dimensional computer navigation was used during the procedures. All patients underwent CT examinations within 6 months postoperation. The CT scans were independently reviewed by three reviewers blinded to the technique used.

Results: The cohort comprised 68 percutaneous and 74 open cases (136 and 148 superior-level pedicle screw placements, respectively). Overall, superior-level FVs occurred in 20 patients (20/142, 14.1%), involving 27 top screws (27/284, 9.5%). The percutaneous technique (7.4% of patients, 3.7% of top screws) had a significantly lower violation rate than the open procedure (20.3% of patients, 14.9% of top screws). The open group also had significantly more serious violations than did the percutaneous group. Both groups had a higher violation rate when the cranial fixation involved the L5. A 1-level open procedure had a higher violation rate than did the 2- and 3-level surgeries.

Conclusions: With computer-assisted navigation, the placement of top-loading percutaneous screws carries a lower risk of adjacent-FVs than does the open technique; when FVs occur, they tend to be less serious. Performing a single-level open lumbar fusion, or the fusion of the L5-S1 segment, requires caution to avoid cranial adjacent FVs.