Meta-analysis finds higher rate of accuracy in robotic pedicle screw placement

Ahmad Tarawneh

Robot-assisted technology was found to be superior to freehand techniques for the placement of pedicle screws in a systematic review and meta-analysis of seven randomised controlled trials involving spinal surgery. However the analysis, published in the Global Spine Journal, concluded that despite the superiority of robot-assisted techniques in screw accuracy, the freehand technique showed superior results in terms of overall surgical duration and revision rates.

Authored by Ahmad M Tarawneh (Nottingham University Hospitals NHS Trust, Nottingham, UK), the review aimed to explore the differences in pedicle screw positioning in terms of accuracy, surgical time, length of hospital stay, postoperative back and leg Visual Analog Scale, revision surgeries and intraoperative radiation time and exposure between robot-assisted technology and conventional freehand techniques.

Tarawneh identified eligible articles up to June 2019 from databases, including the Cochrane library, PubMed, and EMBASE. Inclusion criteria determined that randomised trials involving robot-assisted screw placement and freehand technique should be included, and involve patients presenting with spinal pathologies mandating pedicle screw placement. Six randomised trials identified by Tarawneh studied the accuracy rate of screw insertion using the Gertzbein-Robbins grading system. Within this group, more than 90% of screws inserted using robot-assisted technology were in grade A—meaning that the screw insertion was inserted with no breach of the cortical layer of the pedicle—compared with 86.4% of screws in the freehand technique. Meanwhile, six studies reported that a total of 97% of screws inserted using the robotic-assisted technique were in A or B grade—where there is a potential breach the cortical layer, although not exceeding it laterally by more than 2mm—compared with 95.4% using the freehand technique. Additionally, 31 screws out of 1,140 screws (2.7%) inserted using the robotic-assisted technique were in Gertzbein-Robbins grades C, D, or E compared with 4.5% (n = 53/1176) using the freehand technique.

Looking beyond the screw accuracy, five of the trials mentioned the overall surgical time from skin to skin. All the studies were in favour of the freehand technique, except one study that showed equal results. The intraoperative radiation exposure was measured by both direct operational outputs recorded by the C-arm in two studies, which showed a statistically significant difference between the two groups in favour of robot-assisted technology, Tarawneh reported.

Considering the findings of the analysis, Tarawneh wrote that robot-assisted technology was associated with equivalent results in terms of length of hospital stay, postoperative back VAS, postoperative leg VAS, and grade (C+D+E) screw insertion accuracy. He noted: “It was demonstrated that the robot-assisted technique is superior to the conventional freehand technique in terms of grade (A) and grade (A+B) screw accuracy and in the reduction of intraoperative radiation time and exposure. On the other hand, the freehand technique showed superior results in terms of overall surgical duration and revision rates.

“Robotics in spine surgery holds a promising future. However, the effectiveness of robotics in spinal instrumentation has been researched less than might be expected. This systematic review and meta-analysis provided an evaluation of the available RCTs on the outcome of pedicle screw insertion using the robot-assisted technique and the conventional freehand technique. To validate the beneficial role of robotics in spine surgery more RCTs with higher sample sizes are encouraged.”

However, Tarawneh acknowledged several points in relation to the findings, first that robot-assisted technology was studied regardless of the robot manufacturer, and that the method of screw placement was studied without taking into account the surgical approach used (open versus minimally invasive, for example) and their effects on the surgical outcome. “The limitation of this study is that it included pedicle screw insertion regardless of the underlying pathology. Future research specifying the accuracy rate in relation to the pathology (trauma, degenerative, and deformity) is needed,” Tarawneh noted.


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