Article Abstract

Navigation accuracy comparing non-covered frame and use of plastic sterile drapes to cover the reference frame in 3D acquisition

Authors: Donald S. Corenman, Eric L. Strauch, Grant J. Dornan, Eric Otterstrom, Lisa Zalepa King


Background: Advancements in surgical navigation technology coupled with 3-dimensional radiographic data have significantly enhanced the accuracy and efficiency of spinal fusion implant placement. Increased usage of such technology has led to rising concerns regarding maintenance of the sterile field, as makeshift drape systems are fraught with breaches thus presenting increased risk of surgical site infections (SSIs). A clinical need exists for a sterile draping solution with these techniques. Our objective was to quantify expected accuracy error associated with 2MM and 4MM thickness Sterile-Z Patient Drape® using Medtronic O-Arm® Surgical Imaging with StealthStation® S7® Navigation System. Camera distance to reference frame was investigated for contribution to accuracy error.
Methods: A testing jig was placed on the radiolucent table and the Medtronic passive reference frame was attached to jig. The StealthStation® S7® navigation camera was placed at various distances from testing jig and the geometry error of reference frame was captured for three different drape configurations: no drape, 2MM drape and 4MM drape. The O-Arm® gantry location and StealthStation® S7® camera position was maintained and seven 3D acquisitions for each of drape configurations were measured. Data was analyzed by a two-factor analysis of variance (ANOVA) and Bonferroni comparisons were used to assess the independent effects of camera angle and drape on accuracy error.
Results: Median (and maximum) measurement accuracy error was higher for the 2MM than for the 4MM drape for each camera distance. The most extreme error observed (4.6 mm) occurred when using the 2MM and the ‘far’ camera distance. The 4MM drape was found to induce an accuracy error of 0.11 mm [95%CI (0.06, 0.15), P<0.001] relative to the no drape testing, regardless of camera distance. Medium camera distance produced lower accuracy error than either the close [additional 0.08 mm error, 95% CI (0.00, 0.15), P=0.035] or far [additional 0.21 mm error, 95% CI (0.13, 0.28), P<0.001] camera distances, regardless of whether a drape was used.
Conclusions: In comparison to the ‘no drape’ condition, the accuracy error of 0.11 mm when using a 4MM film drape is minimal and clinically insignificant.