A new study published in the Journal of Neurosurgery: Spine indicates that the percutaneous placement of pedicle screws is associated with an increased risk of facet joint violation, even when only proximal screws are considered, compared with open placement techniques.
Sean Jones-Quaidoo, Norton Leatherman Spine Center, Louisville, USA, and others reported that percutaneous pedicle screw placement has grown in popularity following the development of minimally invasive lumbar fusion techniques. However, they added that percutaneous screws are usually placed with 2D radiographic imaging and, therefore, anatomical landmarks are not directly visualised. Jones-Quaidoo et al commented: “Several recent studies have raised concern that these techniques may have a higher incidence of violation of the superior cephalad, unfused facet joint. Continued motion at this joint with instrumentation within the joint could theoretically lead to accelerated facet degeneration and premature adjacent-segment changes.”
Previous studies have only compared percutaneous screw placement with historical controls; therefore, the authors of the present study aimed to compare the rate of superior or facet joint violation in percutaneous screw placement with the rate in open screw placement. Patients were included in the study if they had undergone single-level lumbar fusion with posterior pedicle screw instrumentation placed in combination with a minimally invasive transforaminal lumbar interbody fusion or in combination with an anterior or lumbar interbody fusion from L-1 to S-1 via apercutaneous approach (percutaneous group) or if they had undergone single-level lumbar fusion with pedicle screws placed through an open approach (control group). All patients had to have undergone CT scanning within one year of surgery.
Of 132 patients overall (after being matched for levels fused), 66 patients were in the percutaneous group (264 screws) and 66 (263 screws) were in the control group. Jones-Quaidoo et al reported: “When all screws were analysed, 36 of 264 screws in the percutaneous and 16 of 263 screws in the open group were in the facet joint (p=0.005). When only the cephalad screws were analysed, 17 of the 132 proximal screws in the percutaneous group and seven of the 131 screws in the open group were in the facet joint (p=0.052).” However, there were no significant differences between the groups in the rate of facet joint abutment with the screw head, connector, or rod even when only cephalad screws were considered.
According to the authors, their study indicates that percutaneous pedicle screw instrumentation—“while preserving the surrounding soft tissues”—may have a “unique set of risks associated with it, most notably cephalad joint violation.” They added further studies are needed to determine if this higher risk of facet joint violation increases the risk of symptomatic adjacent-level disease.