Transsacral screw fixation for high-grade spondylolisthesis.

Background Context: Symptomatic high-grade spondylolisthesis (Meyerding III-V) is usually treated by surgery. Recent literature shows that in situ fusion is better than reduction of the slip and fusion in high-grade spondylolisthesis. Furthermore, the outcome is improved if circumferential fusion is performed in severe spondylolisthesis. We have performed a new technique of circumferential fusion in high-grade spondylolisthesis using two transsacral hollow modular anchorage (HMA) screws supplemented with pedicle screw fixation and posterolateral fusion.

Purpose: The aim of the study is to analyze the results of circumferential fusion using transsacral HMA screws supplemented with posterolateral fusion and pedicle screw fixation.

Study Design: Retrospective study.

Patient Sample: Twelve patients with high-grade spondylolisthesis were reviewed.

Outcome Measures: Outcome was measured using short form 36 (SF-36) and the ability to return to work at the most recent follow-up.

Methods: All patients had interbody fusion using transsacral HMA screws filled with cancellous bone graft and supplemented with pedicle screw instrumentation and posterolateral fusion.

Results: The male to female ratio was 2:1 with a mean age of 31 years (range 13-54 years). Eleven of 12 patients had disappearance of leg pain. There were no neurological complications in any of them. Circumferential fusion was achieved in all of them at a mean follow-up of 21 months. The average physical function score improved from 22.50+/-10.34 to 57.50+/-17.39 (p=.001, 95% confidence interval [CI] -44.48 to -25.52), whereas the average pain score improved from 22.22+/-13.40 to 61.11+/-15.35 (p=.001, 95% CI -51.12 to -26.66).

Conclusions: HMA screws avoid the complications associated with autologous cortical fibular strut graft and also are useful to promote interbody fusion, as the hollowness in the screw can be filled with cancellous bone graft that helps in better fusion. Supplementary pedicle screw fixation is necessary to protect the HMA screws, and they together give a stable construct that can achieve a circumferential fusion in high-grade spondylolisthesis.