Transdiscal screw versus pedicle screw fixation for high-grade L5-S1 isthmic spondylolisthesis in patients younger than 60 years: a case-control study.

Purpose: To compare outcomes between transdiscal and conventional pedicle fixation for high-grade L5-S1 spondylolisthesis.
Methods: This was a retrospective case-control study with patients prospectively followed. Twenty-five consecutive patients with mean age of 36.7 years underwent transdiscal fixation, and 31 other with mean age of 42.0 years to pedicle fixation were clinically and radiographically compared. Clinical assessments were performed using Oswestry Disability Index (ODI), Core Outcomes Measures Index (COMI), Short-Form 12 (SF-12), and pain visual analog scale (VAS). Radiographic spinopelvic parameters were also evaluated. The mean follow-up was 2.7 years (range 2.0-5.3).
Results: Preoperative data were comparable between groups. Surgery time, blood loss, and hospital stay were similar between groups. At last follow-up, clinical and radiographic outcomes were significantly improved in both groups. Postoperatively, both lumbar and leg pain VAS were similar between groups, but ODI (20.2 vs. 31.6, p = 0.010), COMI (1.6 vs. 2.8, p = 0.012), and SF-12 physical (84.3 vs. 61.5, p = 0.004) and mental (81.5 vs. 69.4, p = 0.021) scores were significantly better in the transdiscal group. The neurologic complication rate was similar in both groups. There were 4 pseudoarthroses in the pedicle group, and none in the transdiscal group.
Conclusion: L5-S1 transdiscal screw fixation provided better functional and radiographic outcomes at medium-term than conventional pedicle fixation for high-grade spondylolisthesis, although transdiscal sacral screws are difficult to place in correct position.