Reduction and fusion in high-grade L5-S1 spondylolisthesis by a single posterior approach. Results in 50 patients.

Introduction: Treatment strategies in high-grade L5-S1 spondylolisthesis are controversial. Reduction of slippage, correction of lumbosacral kyphosis and the necessity of a complementary anterior approach are debated in the literature. The present study reports clinical and radiological outcome for reduction and instrumented fusion on a single posterior approach.

Material And Method: A retrospective study included all consecutive adolescent and young adult patients operated on by a single surgeon (D.C.) for high-grade (Meyerding 3-4-5) L5-S1 spondylolisthesis. The technique consisted in reduction of lumbosacral kyphosis and posterolateral fusion on a single posterior approach without resection of the sacral dome or complementary anterior approach. Only cases of adult ptosis required impacted tibial interbody graft. Clinical complications, radiologic lumbopelvic results and sagittal balance were analyzed at last follow-up.

Results: Fifty patients, with a mean age at surgery of 21±11 years, were followed up for a mean 5.5±4.6 years. Mean lumbosacral angle was reduced by 25° (from 76° to 101°; P<0.05), and mean listhesis grade by >50% (from 75% to 23%; P<0.0001), without correction loss at last follow-up. C7 sagittal offset was corrected (from 8° to 4°; P<0.05), with harmonization of lumbar (from 57° to 64°; P<0.001) and thoracic curvature (from 37° to 44°; P=0.1). Seventeen patients (34%) showed postoperative radicular deficit, without sequelae at last follow-up. There were no cauda equina lesions. Bone fusion was achieved in 42 patients (84%), in the same surgical step. After revision by complementary interbody graft, there was no residual non-union.

Conclusion: Surgery on a single posterior approach gave reliable results in high-grade spondylolisthesis in adolescents and young adults. The technique is not however, free of risk (transient neurologic deficit and non-union), and patients should be forewarned. Complementary interbody graft can be reserved to adult ptosis with incomplete reduction of lumbosacral kyphosis and to revision surgery for non-union.

Level Of Evidence: IV, retrospective study.