Bilateral pedicle screw fixation combined with interbody fusion for the treatment of lumbar spondylolisthesis (degree II or III) through muscle-splitting approach

Abstract

Objective To investigate the feasibility and effectiveness of bilateral pedicle screw fixation combined with interbody fusion for the treatment of lumbar spondylolisthesis (degree II or III) through muscle-splitting approach. Methods There were 52 patients (16 males and 36 females) analyzed in our study from January 2012 to December 2015. The average age was 54.9±7.21 years (from 35 to 70 years). The history of disease was from 10 months to 15 years, with an average of 66.6±32.71 months. Diagnosis included: degenerative spondylolisthesis in 2 cases, and isthmic spondylolysis in 50 cases. The sites included L4,5 in 18 cases and L5S1 in 34 cases. The degree was II in 35 cases and III in 17 cases. 27 cases were treated by bilateral pedicle screw fixation combined with interbody fusion through median incision approach (open group) and 25 cases through muscle-splitting approach (minimally invasive group). The clinical and imaging results were observed and compared between the two groups, including operation time, intraoperative blood loss, postoperative incision drainage, VAS score of lumbar incision pain at 72h post-operative, intraoperative and postoperative complications, interbody fusion rate, multifidus muscle areas and grades at 1 year post-operative, and the improvement of ODI index. Results All the cases were operated successfully. The operation time of open group was shorter than minimally invasive group. However, the intraoperative blood loss and postoperative incision drainage of minimally invasive group was statistically less than open group. The VAS scores of postoperative 72 h were 3.25 (2 to 6) in open group and 1.62 (1 to 3) in minimally invasive group. And the difference was statistically significant. The misplacement rate of pedicle screws of minimally invasive group was lower than open group. The average follow-up time was 25.5 months (ranged from 12 to 36 months). The multifidus muscle areas and grades of minimally invasive group were superior to open group at 1 year postoperatively. Compared to preoperative, the slipping angle, slipping rate, sacral inclination angle and vertebral space height were significant improved after operation in two groups. The ODI index was improved postoperatively in both two groups, and the difference was statistically significant at the final follow-up. The interbody fusion rate was 92.6% in open group and 96% in minimally invasive group, and there was no significant difference between the two groups. No cerebrospinal fluid leak, never injury, pedicle fracture or wound infection was found after the operation in two groups. There was no pedicle screw loosening, cage shifting, or degeneration of the adjacent segment observed during follow-up. Conclusion Bilateral pedicle screw fixation combined with interbody fusion through muscle-splitting approach has advantages of small incision, less trauma, less bleeding, quick recovery and well clinical results, which can be a better choice in treating lumbar spondylolisthesis (degree II or III). Key words: Lumbar vertebrae; Spondylolysis; Surgical procedures, minimally invasive; Spinal fusion