Segmental Surface Referencing during Intraoperative Three-dimensional Image-Guided Spine Navigation: An Early Validation with Comparison to Automated Referencing

Abstract

Study Design Interventional human cadaver study. Objective Intraoperative three-dimensional (3-D)-guided navigation improves spine instrumentation accuracy. However, image acquisition may need to be repeated with segment hypermobility or distant target from reference frame (RF). The current study evaluates the usefulness of internal metal fiducials (IMFs) as surface references in enhancing registration accuracy and avoiding repeating imaging. Methods Six fresh-frozen cadaveric human torsos were utilized. Posterior C1–T2 exposure was done, and three IMFs were inserted per level; intraoperative 3-D images were then acquired. Two registration methods were utilized: autoregistration (AR, group 1) and point registration using IMF (IMFR, group 2). Registration accuracy was checked by identifying IMFs in both groups. Pedicle screws inserted into C2, C4, C5, and C7 based on the two registration methods (three cadavers each) with RF on C7 and then on C2. Results The mean registration error was lower with IMFR compared with AR (0.35 ± 0.5 mm versus 2.02 ± 0.85 mm, p = 0.0001). Overall, 34 pedicle screws were inserted (AR, 18; IMFR, 16). Final screw placement was comparable using both techniques (p = 0.58). Lateral screws violations were observed in four IMFR screws (1 to 2 mm) as compared with five in AR group (2 to 3 mm). Reregistration after moving RF to C2 was possible using surface screws in IMFR group, thus avoiding new 3-D image acquisition. Conclusion During intraoperative 3-D navigation in spine procedures, surface fiducial registration using IMF provided superior accuracy over automated registration. It allowed repeat registration without repeating radiation during long spine segment instrumentations. More studies are needed to clarify both practical and clinical application of this method.

Correction of Severe Stiff Scoliosis Through Extrapleural Interbody Release and Osteotomy (Liepo)

“…[8][9][10] The literature shows that historically patients with curves greater than 70°, or those who remain at magnitudes greater than 50° in lateral inclination tests, should be operated by combined approach in order to perform anterior ligament release associated with correction via posterior approach. Thus, Li et al 2 achieved a correction rate of 48.6% in their series of 31 cases with an average preoperative Cobb of 98°.…”

Ultrasound propagation characteristics within the bone tissue of miniature ultrasound probes: implications for the spinal navigation of pedicle screw placement

“…Position changes can easily lead to registration errors. Although advanced navigation technologies such as O-arm navigation can provide immediate intraoperative three-dimensional (3D) computed tomography (CT) images and perform fully automatic registration, there are certain drawbacks, including an increased scanning time and repeated radiation exposure during surgery ( 12 ). Robot-assisted techniques incurs higher costs while offering comparable accuracy ( 13 ) in screw placement to the aforementioned navigation devices.…”