Object: Recent studies have reported the incidence of superior facet joint violation using percutaneous techniques. These techniques have not been compared with the open midline approach. An increased incidence of superior facet violation may lead to adjacent-segment disease. In this paper, the authors' goal is to compare the rate of superior facet violation with the use of percutaneously placed pedicle screws versus midline approach open placement.
Methods: Patients who underwent a single-level fusion using a percutaneous approach from L-1 to S-1 who had undergone CT scanning within 1 year after surgery were identified. A cohort who underwent open fusion matched by level of surgery was identified. All CT scans were reviewed by 3 fellowship-trained spine surgeons to determine the degree of facet violation. The final categorization for each screw was based on the most frequent reading among the 6 evaluations. The Fisher test was used to determine the association of facet violation with approach.
Results: There were 66 patients in each group. Patients in the Percutaneous group were younger (mean 42.5 years) than those in the Open group (mean 57.8 years, p = 0.000). There was no statistically significant difference in sex distribution, surgical levels fused, or time between surgery and CT scan between the groups. Thirty-six (13.6%) of 264 screws in the percutaneous and 16 (6%) of 263 screws in the Open group were in the facet joint (p = 0.005). Of these, 17 (12%) of the 132 proximal screws in the percutaneous and 7 (5%) of the 131 proximal screws in the Open group were in the facet joint (p = 0.052).
Conclusions: The use of a percutaneous method to insert pedicle screws results in a statistically significantly higher incidence of facet joint violation, even if only proximal screws are considered. Further studies are needed to determine if this leads to a higher incidence of symptomatic adjacent-level disease.