OBJECTIVETo evaluate the validity and reliability of Thread-tooth Arc-track Screw Plate System (TASPS) in the fixation fusion through expandable channels.

METHODSFrom August 2007 to August 2010, 108 patients with lumbar instability were treated with surgery, including 61 males and 47 females, ranging in age from 26 to 57 years, with an average of 41 years. All the patients were divided into two groups : minimally invasive fusion group and traditional operation group (54 patients in each group). The patients in the minimally invasive fusion group were treated with self-designed TASPS to conduct the fixation fusion through expandable channels by minimally invasive pedicle screw; and the patients in traditional operation group were treated with traditional interbody fixation fusion by pedicle screw. The data were collected and investigated at the 1st week, 3rd month and 1st year postoperatively. The comparative parameters of two groups contained the total operation time, the implanted time, the total amount of bleeding; the VAS score, ODI score and improvement rate at each investigated period; the intervertebral space height of preoperative and postoperative periods; the inefficiency rate of implantation and the fusion rate of postoperative period.

RESULTSAll incisions were healed by first stage without any complications such as dural tear, injury of nerve root or cauda equine, intervertebral space infection. The patients in the minimally invasive fusion group needed longer operative time than that of the traditional operation group, but had less total amount of intraoperative and postoperative bleeding and shorter implanted time of pedicle screw than those of the traditional operation group. The VAS scores of two groups at the 1st week after operation significantly decreased compared with that of the 1st day before the operation, and the difference was of high statistical significance. And the VAS scores of two groups at the 3rd month and 1st year after operation also significantly decreased compared with that of the 1st day before the operation, and the difference was highly statistically significant. By comparing the VAS score and ODI score at the 1st week, 3rd month and 1st year postoperatively, the results showed that the VAS score and ODI score of the minimally invasive fusion group were all lower than those of the traditional operation group, and the differences were of high statistical meaningfulness. After 1 year, the improvement rate of the minimally invasive fusion group was (77.46 +/- 6.34)%, while that of the traditional operation group was (72.73 +/- 4.49)%, and the difference was highly statistically significant (P < 0.01). The intervertebral space heights of two groups remarkably increased. At the 3rd month after operation, the difference of intervertebral space heights of the two groups was of no statistical significance. At the 1st year after operation, intervertebral space heights of the two groups were lost to some extent, but the height of the minimally invasive fusion group was higher than that of the traditional operation group, and the difference was statistically significant. The fusion rates of the two groups after 1 year were 100%.

CONCLUSIONThe fixation fusion through expandable channels by minimally invasive pedicle screw possesses the characteristics of fewer traumas, less intraoperative blood loss, less postoperative pain and rapid recovery. Since its intervertebral fusion rate is similar to the open surgery, it can be viewed as one effective approach for the treatment of lumbar instability diseases. And TASPS is reasonably designed, easy to install and reliably fixed with good reduction effect, which can be applied through expandable channels.