【Abstract】 Objective To study the effectiveness of computer assisted pedicle screw insertion in osteoporotic spinalposterior fixation. Methods Between December 2009 and March 2011, 51 patients underwent pedicle screw fixation using the computer assisted navigation (navigation group), while 41 patients underwent the conventional technique (traditional group). All patients had osteoporosis under the dual-energy X-rays absorptiometry. There was no significant difference in age, gender, bone mineral density, involved segment, preoperative complications, and other general status between 2 groups (P gt; 0.05). The amount of blood loss, the operation time, the rate of the pedicle screw re-insertion, and the postoperative complication were observed. The state of the pedicle screw location was assessed by CT postoperatively with the Richter’s classification and the fusion state of the bone graft was observed using three-dimensional (3-D) CT scans during follow-up. Results A total of 250 screws were inserted in navigation group, and 239 were inserted successfully at first time while the other 11 screws (4.4%) were re-inserted. A total of 213 screws were inserted in traditional group, and 190 were successful at first time while 23 screws (10.8%) were re-inserted. There was significant difference in the rate of screws re-insertion between 2 groups (χ2=6.919, P=0.009). Both the amount of blood loss and the operation time in navigation group were significantly less than those in traditional group (P lt; 0.05). According to Richter’s classification for screw location, the results were excellent in 240 screws, good in 10 screws innavigation group; the results were excellent in 191 screws, good in 21 screws, and poor in 1 screw in traditional group. Significant difference was noticed in the screw position between 2 groups (χ2=7.566, P=0.023). The patients were followed up (7.8 ± 1.5) months in navigation group and (8.7 ± 1.5) months in traditional group. No loosening, extraction, and breakage of the pedicle screw occurred in navigation group, and all these patients had successful fusion within 6 months postoperatively. While in traditional group, successful fusion was shown in the other patients by 3-D CT, except the absorption of bone graft was found in only 1 patient at 6 months after operation. And then, after braking by adequate brace and enhancing the anti-osteoporotic therapy, the bone graft fused at 9 months postoperatively. Conclusion The computer assisted navigating pedicle screw insertion could effective reduce the deviation or re-insertion of the screws, insuring the maximum stabil ity of each screw, mean while it can reduce the exposure time and blood loss, avoiding complication. The computer assisted navigation would be a useful technique which made the pedicle screw fixation more safe and stable in patients with osteoporosis.
ObjectiveTo evaluate the value of computer assisted navigation system (CANS) in the reconstruction of mandibular defects. MethodsBetween April 2012 and September 2014, 8 patients with mandibular defects were included in this study. There were 5 males and 3 females with an age range of 22-50 years (mean, 34.5 years), including 4 cases of ameloblastoma, 3 cases of odontogenic keratocyst, and 1 case of condylar osteoma. According to the CRABS (condyle, ramus, angle, body, symphysis) classification criteria based on the location of mandibular defect, there were 1 case of right CRAB type, 1 case of left RABS type, 1 case of left CR type, 1 case of right RAB type, 1 case of left C type, 1 case of right RABS+left S type, and 2 cases of right AB type. With the biteplate fixing mandible, maxillofacial CT and the donor site CT scan were done. Computer assisted design was made by using Surgicase CMF5.0 software and BrainLab Iplan software, included delineating the osteotomy lines for resection, ascertaining the normal anatomic structures for defect reconstruction, and determining the reconstructive morphology. With guide plates and the guidance of BrainLab navigation system, an en bloc tumor resection and simultaneous defect reconstruction were performed under the precise localization of mandibular angle and condyle. Preoperative and postoperative CT images were superimposed in Geomagic studio12.0 software system, and both were compared by three-dimensional (3D) objects and 2D slices. The complications and signs of recurrence were observed. ResultsUnder the guidance of navigation, preoperative facial symmetry design, surgery simulation, and simultaneous navigation operation were performed successfully. The postoperative CT and postoperative 3D error analysis showed osteotomy lines and reconstruction contour had good matching with the preoperative planning. The error of important corresponding points (mandibular angle and external pole of condyle) in the reconstruction of mandibular defects were (1.83±0.19) mm and (1.61±0.24) mm. The patients were followed up 2-6 months (mean, 3.5 months). No complication was observed in the other patients except the patients undergoing rib transplantation who had mild limitation of mouth opening. Good facial symmetry was obtained, and no tumor recurrence was found. ConclusionCANS can effectively increase the surgical precision in the reconstruction of mandibular defects and reduce complications, and recover facial symmetry. It is regarded as a valuable technique in this potentially complicated procedure.