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Study Design: A porcine model.Objective: The study aims to design a novel pedicle navigator based on micro-inertial navigation system (MINS) and bioelectrical impedance analysis (BIA) to assist place pedicle screw placement and validate the utility of the system in enhancing pedicle screw placement.Summary Of Background Data: The incidence of pedicle screw malpositioning in complicated spinal surgery is still high.Procedures such as computed tomography image-guided navigation, and robot-assisted surgery have been used to improve the precision of pedicle screw placement, but it remains an unmet clinical need.Methods: The miniaturized integrated framework containing MINS was mounted inside the hollow handle of the pedicle finder. The inner core was complemented by a high-intensity electrode for measuring bioelectric impedance. Twelve healthy male Wuzhishan minipigs of similar age and weight were used in this experiment and randomized to the MINS-BIA or freehand (FH) group. Pedicle screw placement was determined according to the modified Gertzbein-Robbins grading system on computed tomography images. An impedance detected by probe equal to the baseline value for soft tissue was defined as cortical bone perforation.Results: A total of 216 screws were placed in 12 minipigs. There were 15 pedicle breaches in the navigator group and 31 in the FH group; the detection rates of these breaches were 14 of 15 (93.3%) and 25 of 31 (80.6%), respectively, with a statistically significant difference between groups. The mean offsets between the planned and postoperatively measured tilt angles of the screw trajectory were 4.5° ± 5.5° in the axial plane and 4.8° ± 3.3° in the sagittal plane with the navigator system and 7.0° ± 5.1° and 7.7° ± 4.7°, respectively, with the FH technique; the differences were statistically significant.Conclusion: A novel and portable navigator based on MINS and BIA could be beneficial for improving or maintaining accuracy while reducing overall radiation exposure. [ABSTRACT FROM AUTHOR]

3 Haffer H, Muellner M, Chiapparelli E. Bone quality in patients with osteoporosis undergoing lumbar fusion surgery: analysis of the MRI-based vertebral bone quality score and the bone microstructure derived from microcomputed tomography. B TO THE EDITOR: b Concerning the Article "MRI-based Score for Assessment of Bone Mineral Density in Operative Spine Patient" Kim and colleagues utilized the magnetic resonance imaging-based vertebral bone quality (VBQ) score to differentiate between healthy and osteoporotic vertebrae and validated the VBQ score against bone mineral density measured by quantitative computed tomography (QCT).[1] The QCT-based I T i -scores were separated into healthy bone ( I T i -score >=-1), osteopenia (-1> I T i -score >-2.5), and osteoporosis ( I T i -score <=-2.5). [Extracted from the article]

TO THE EDITOR: Concerning the Article: Should Q-CT Be the Gold Standard for Detecting Spinal Osteoporosis? The diagnostic criteria recommended by the WHO in 1994 was used to establish the diagnosis of osteoporosis (normal, -1.0 or above; osteopenia, between -1.0 and -2.5; osteoporosis, -2.5 or below). Arvind compared the I T i -scores of the bone densities measured by two different methods: spinal quantitative computed tomography (QCT) and dual-x ray absorptiometry (DXA). [Extracted from the article]