Junior Specialist UC Irvine Department of Neurosurgery Santa Clarita, California, United States
Introduction: Lateral lumbar interbody fusion (LLIF) including the anterior-to-psoas oblique lumbar interbody fusion (OLIF) has conventionally relied on percutaneous pedicle screw placement (PSP) for construct stabilization. Single-position surgery with lumbar interbody fusion (LIF) in the lateral decubitus position with concomitant PSP has been associated with increased operative efficiency. What remains unclear is the accuracy of PSP with robotic guidance when compared to the more familiar prone patient positioning. The present study aims to compare robot-assisted screw placement accuracy between patients instrumented in the prone and lateral positions.
Methods: We identified all consecutive patients treated with interbody fusion and PSP in the prone or lateral position by a single surgeon between January 2019 and October 2022. All pedicle screws placed were analyzed using CT imaging to determine appropriate positioning according to the Gertzbein-Robbins Classification Grading System (grade C or worse was considered as a radiographically significant breach). Multivariate logistic regression models were constructed to identify risk factors for the occurrence of a radiographically significant breach.
Results: Eighty-nine consecutive patients were included (n=690 screws), of whom 46 were treated in the prone position (n=477 screws) and 43 in the lateral decubitus position (n=213 screws). There were fewer breaches in the prone (n=13; 2.7%) versus lateral decubitus group (n=15; 7.0%; p=0.012). Nine (1.9%) radiographically significant breaches occurred in the prone group compared to 10 (4.7%) in the lateral decubitus group (p=0.019), for a prone vs. lateral decubitus pedicle screw accuracy rate of 98.1% vs. 95.3%. In multivariate models, prone position was the only significant protective factor for screw accuracy; we did not identify any other significant risk factors for screw breach.
Conclusion : Our data suggests that pedicle screws placed with robotic assistance have higher placement accuracy in the prone position.
How to Improve Patient Care: The present study is to our knowledge the largest direct comparison of screw accuracy in the lateral and prone positions and helps to further inform the relative merits of the single-position lateral and single-position prone approaches for lumbar spine surgery. Additional investigation of the long-term sequelae of screw misplacement are necessary, though the present results argue favorably for the continued use of single-position prone approaches.
