3D Printed Guides vs Drill Guiding. Which Is Better?

A new study from the University of Groningen in the Netherlands compared the accuracy of 3D-printed drill guides vs additional screw guiding techniques for those difficult intra- and extra-pedicular spine screw trajectories. Which is better? The research team concluded that adding screw-guiding techniques to the regular 3D-printed drill guides did NOT offer any significant benefits. Interesting.

The study, “A Comparison of Drill Guiding and Screw Guiding 3D-Printing Techniques for Intra- and Extrapedicular Screw Insertion,” was published online in the May 15, 2022 issue of the journal Spine.

The Groningen team compared the accuracy of three-dimensional-printed drill guides to additional screw guiding techniques in cases where the surgeon is confronted by challenging intra- and extra-pedicular screw trajectories.

“Pedicle screw placement can be technically demanding, especially in syndromic scoliosis with limited bone stock. Recently, 3D-printing, and virtual planning technology have become available as new tools to improve pedicle screw insertion. Differences in techniques exist, while some focus on guiding the drill, others also actively guide subsequent screws insertion,” the researchers wrote.

“The accuracy of various 3D-printing-assisted techniques has been studied; however, direct comparative studies have yet to determine whether there is a benefit of additional screw guidance.”

In two cadaveric experiments were conducted to compare drill guides with two techniques that introduce additional screw guiding. The screw guiding consisted of either k-wire cannulated screws or modular guides.

Using a randomization scheme, they inserted the screws either intra- or extra-pedicular. Then they conducted a detailed 3D screw deviation analysis.

For intra-pedicular screw trajectories malpositioning was low and the modular guides revealed a statistically significant increase of accuracy (p = 0.05) compared with drill guides.

All techniques showed accurate cervical screw insertion without breach. For the extra-pedicular screw trajectories, both additional screw-guiding methods did not significantly (p = 0.09) improve accuracy and malpositioning rates remained high.

“In this cadaveric study it was found that the additional screw-guiding techniques are not superior to the regular 3D-printed drill guides for the technically demanding extra-pedicular screw technique. For intra-pedicular screw insertion, modular guides can improve insertion; however, at cervical levels regular 3D-printed drill guides already demonstrated very high accuracy and therefore there is no benefit from additional screw-guiding techniques.”

The study authors included Peter A.J. Pijpker, MSc, Joseph Kuijlen, M.D., Ph.D., Joep Kraeima, Ph.D., Rob J.M. Groen, M.D., and Chris Faber, M.D., Ph.D., all of the University of Groningen, University Medical Center Groningen, The Netherlands.