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Study Design. An experimental investigation of a robot-assisted ultrasonic osteotome applied to vertebral cancellous bone. Objective. The aim of this study was to investigate the effect of various ultrasonic parameter settings on temperature in the drilling site and penetration time and determine the most suitable parameters for efficient and safe robot-based ultrasonically assisted bone drilling in spinal surgery Summary of Background Data. A robot-assisted ultrasonic osteotome device may be safe and effective for spinal drilling. Methods. Sixty specimens of bovine vertebral cancellous were randomly assigned to one of six groups, which varied by mode of ultrasonic vibration (L-T and L) and feed rate (one percent [0.8 mm/s], two percent [1.6 mm/s], and three pecent [2.4mm/s]). Maximum temperature in the drilling site and penetration time was recorded. Results. Maximum temperature in the drilling site decreased as output power increased for L-T and L modes, was significantly lower for L-T compared to L mode at each feed rate and power setting, was significantly different at feed rates of 1.6 mm/s versus 0.8 mm/s and 2.4 mm/s versus 0.8 mm/s for L-T mode at an output power of 60 W and 84 W, but was not influenced by feed rate for L mode. Penetration time did not significantly improve as output power increased for both L-T and L modes, was significantly decreased with increased feed rates, but was not significantly different between L-T and L modes. Conclusion. The optimal parameters for applying a robotassisted ultrasonic osteotome to vertebral cancellous bone are LT mode, maximum output power of 120 W, and maximum feed rate of 2.4 mm/s. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective comparative cohort series.Objective: To evaluate the accuracy and feasibility of minimally invasive surgical (MIS) techniques incorporating with intraoperative 3-dimensional fluoroscopy-based navigation (ITFN) for treating Hangman fracture.Summary Of Background Data: MIS screw fixation for Hangman fracture can decrease iatrogenic soft-tissue injury, but increase the risk of instrumentation-related complications due to lack of anatomical landmarks. With the advantages of obtaining intraoperative real-time images, automatic registration, and 3-dimensional views, the ITFN system seems to be an inherent partner for MIS.Methods: 20 patients with Hangman fracture underwent C2-C3 pedicle screw fixation using ITFN. 6 patients used MIS technique, with the other 14 patients using conventional open technique. Operative time and blood loss were recorded. The accuracy of screw positions was studied by postoperative CT scan. Neck pain visual analogue score (VAS) was evaluated and the fusion status was ascertained in 6-month follow-up.Results: The average operative time was 134.2 ± 8.0 minutes in computer-assisted orthopaedics surgery (CAOS)-MIS group and 139.3 ± 25.8 minutes in CAOS-open group (P > 0.01). The blood loss was 66.7 ± 25.8 mL in CAOS-MIS group and 250.0 ± 141.4 mL in CAOS-open group (P < 0.01). A total of 80 screws were inserted. No screw-related neurovascular injury was observed. 83.3% (20/24) screws in CAOS-MIS group and 89.3% (50/56) screws in CAOS-open group were grade 1 screw (P > 0.01). No grade 3 screw was detected in both groups. Compared with the CAOS-open group (1.7 ± 0.6), neck pain VAS in 6-month follow-up in CAOS-MIS group (0.3 ± 0.5) was significantly lower (P < 0.01). Solid fusion was demonstrated in all the cases.Conclusion: The integration of these 2 techniques MIS and ITFN, we call "computer assisted minimally invasive spinal surgery," is proved to be feasible and safe for treating Hangman fracture with the advantage of significantly reduced iatrogenic soft tissue injury. So we think CAMISS technique represents the most recent modification of spine surgery. [ABSTRACT FROM AUTHOR]