Objective: To study the effectiveness of computer assisted pedicle screw insertion in osteoporotic spinal posterior 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 > 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 (chi2 = 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 < 0.05). According to Richter's classification for screw location, the results were excellent in 240 screws, good in 10 screws in navigation 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 (chi2 = 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 stability 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.