Minimally Invasive Pedicle Screw Fixation Using Intraoperative 3-dimensional Fluoroscopy-based Navigation (CAMISS Technique) for Hangman Fracture

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 134.28.0minutes in computer-assisted orthopaedics surgery (CAOS)-MIS group and 139.325.8minutes in CAOS-open group (P>0.01). The blood loss was 66.7 +/- 25.8mL in CAOS-MIS group and 250.0 +/- 141.4mL 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.Level of Evidence: 3