The positional consistency between guidewire and cannulated or solid screw in robot-assisted spinal internal fixation surgery

BACKGROUND

This study aimed to investigate the positional consistency between the guidewire and the screw in spinal internal fixation surgery.

METHODS

This study involved 64 patients who underwent robot-assisted thoracic or lumbar pedicle screw fixation surgery. Guidewires were inserted with the assistance of the Tirobot. Either cannulated screws or solid screws were inserted. Guidewire and screw accuracy was measured using CT images based on the Gertzbein and Robbins scale. The positional consistency between guidewire and screw was evaluated based on the fused CT images, which could graphically and quantitatively demonstrate the consistency. The consistency was evaluated based on a grading system that considered the maximum distance and angulation between the centerline of the guidewire and the screw in the region of the pedicle.

RESULTS

A total of 322 screws were placed including 206 cannulated ones and 116 solid ones. Based on the Gertzbein and Robbins scale, 97.5% of the guidewires were grade A, and 94.1% of the screws were grade A. Based on our guidewire-screw consistency scale, 85% in cannulated group, and 69.8% in solid group, were grade A. Both solid and cannulated screws may alter trajectory compared to the guidewires. The positional accuracy and guidewire-screw consistency in the solid screw group is significantly worse than that in the cannulated screw group. The cortical bone of the pedicle has a positive guide effect on either solid or cannulated screws.

CONCLUSION

The pedicle screws may alter trajectory despite the guidance of the guidewires. Solid screws show worse positional accuracy and guidewire-screw consistency compared with cannulated screws. Trial registration The study was retrospectively registered and approved by our center's institutional review board.

Intraoperative CT Scan Verification of Pedicle Screw Placement in AIS to Prevent Malpositioned Screws: Safety Benefit and Cost

STUDY DESIGN

Prospective database review.

OBJECTIVES

Determine if use of intraoperative 3D imaging of pedicle screw position provides clinical and cost benefit.

SUMMARY OF BACKGROUND

Injury or reoperation from malpositioned pedicle screws in adolescent idiopathic scoliosis (AIS) surgery occurs but is increasingly considered to be a never-event. To avoid complications, intraoperative 3D imaging of screw position may be obtained.

METHODS

A prospective, consecutive AIS database at a high-volume pediatric spine center was examined three years before and after implementation of an intraoperative low-dose computed tomographic (CT) scan protocol. All screws were placed via freehand technique and corrected if found to be outside optimal trajectory on the postplacement CT scan. Demographic and outcome data were compared between cohorts, along with number, location, and reason for screw change. Cost analysis was based on the average cost of revision surgery for screw malposition versus intraoperative CT use.

RESULTS

There were 153 patients in the pre-CT and 153 in the post-CT cohorts with a minimum 2-year follow-up. Two reoperations were needed for revision of improper screw placement in the pre-CT group and none in the post-CT group. Number of patients needed to harm was 76 (absolute risk increase = 1.31% [-0.49%, 3.11%]). Of those who had intraoperative CT scans, 80 (52.3%) needed on average 1.75 screw trajectories/lengths changed. Forty-three percent were medial breaches; of these, 39% were in the concavity. There were no differences between patients who did and did not need screw repositioning with regard to body mass index (BMI), age, curve size, surgeon/trainee side, screw density, or preoperative and one-year postoperative Scoliosis Research Society-22 patient questionnaire (SRS-22) scores. The average cost of reoperation for malposition was $4,900, whereas the cost of a single intraoperative CT was $232.

CONCLUSION

Intraoperative CT is an effective tool to prevent reoperation in AIS surgery for incorrect screw placement. Despite high volume, experience, and specialty training, incorrect trajectories occur and systems should be in place for preventable error.

LEVEL OF EVIDENCE

Level II.

Intra-operative micro-electrode recording in functional neurosurgery: Past, present, future

The field of functional neurosurgery has experienced a rise, fall and lastly a renaissance over the past 75years. Micro-electrode recording (MER) played a key role during this eventful journey. However, as the intra-operative MRI continues to evolve, a pertinent question about the utility of MER has been raised in recent years. In this article, we critically review these current controversies. The English literature is reviewed and the complex technique of MER is discussed in a simplified manner. The improvement of neuroimaging and its application in functional neurosurgery, especially in deep brain stimulation, is discussed. Finally, the current controversies and technical advances which can direct the future are reviewed. The results of existing meta-analyses addressing the controversies are summarized. Wide variations of pre-operative and intra-operative targeting methods have been described in the literature. Though functional neurosurgery is generally safe, complications do occur and multiple passes during MER can certainly add to the risk of inadvertent hemorrhage and infection. Additionally, the recent introduction of newer MRI modalities has ensured better delineation of the target. However, MER is still useful to address brain shift, for mapping of newer targets, for ablative surgeries and in centers without an intra-operative imaging facility. In the current scenario, it is nearly impossible to conduct a prospective study to decide the utility of MER. The importance of MER may further diminish in the future as a routine procedure, but its role as a gold standard procedure may still persist.