Sagittal alignment following a modified Jackson technique in the surgical management of high-grade spondylolisthesis

The optimal surgical management of paediatric high-grade spondylolisthesis (HGS) remains controversial. Instrumented fusion in situ (IFIS) is considered low risk for neurological complications at the expense of limited correction of spinopelvic imbalance. This study evaluated radiographic outcomes of IFIS using a modified Jackson technique, with a focus on sagittal alignment and the evolution of spinopelvic balance over time.

A retrospective review of 19 patients (< 18 years, mean age 13.7) with ≥ grade 3 HGS treated with IFIS using a modified Jackson technique between 2006 and 2022. Radiographic parameters including slip percentage, pelvic incidence, sacral slope, pelvic tilt, lumbosacral angle, and balance classification were analysed at baseline, 6 months, and 2 years post-operatively. Subgroup analysis was performed for patients with vertical versus non-vertical sacrum morphology. Mixed-measures ANOVA determined changes across time points.

Improvements in sagittal parameters were progressive, with more substantial changes observed at 2 years than at 6 months, suggesting gradual improvement over time. Significant improvements were observed in slip percentage (p < 0.001), sacral slope (p = 0.005), pelvic tilt (p = 0.016), lumbosacral angle (p < 0.001), and L5 incidence (p = 0.019). Patients presenting with a vertical sacrum showed greater increases in sacral slope and reduction in pelvic retroversion.

The results of IFIS using a modified Jackson technique for paediatric HGS suggests significant partial improvements in key sagittal alignment parameters, including SS, PT, and LSA at 2-year follow-up. Whilst pelvic balance often remained incomplete at 2 years, ongoing radiographic improvement suggests a potential for further adaptation with longer follow-up.

Level IV.