Stabilization of L5 pedicle Subtraction osteotomies (PSO) with ≥ 6-rods and bilateral dual pelvic fixation with osseointegrative implants: surgical technique description and early postoperative outcomes.

Brumm, Zachary; Clark, Aaron J; Theologis, Alekos A · Eur Spine J · 2025

case_series · Level IV

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Abstract

To introduce and report early outcomes of an innovative surgical strategy to stabilize L5 PSOs with minimum 6 rods utilizing bilateral dual pelvic fixation consisting of both traditional iliac screws and osseointegrative S2AI screws. Adult patients at a single institution who underwent a L5 PSO reconstructed with a minimum of 6 rods using dual pelvic fixation were reviewed. Accompanying a description of the surgical technique is patient demographics, perioperative sagittal radiographic alignment parameters, and early surgical and clinical outcomes, including incidences of mechanical complications. Seven patients (4 females; average age 68 ± 8 years) met inclusion criteria. In addition to the L5 PSO, operative strategies were mixed [86% revisions, 86% lower thoracic UIV, 86% interbodies (ALIF, TLIF, DLIF) at either L3-4, L4-5, and/or L5-S1]. Average L5 PSO angle was 34.1<sup>0</sup> ± 3.2<sup>0</sup> (range, 30-39<sup>0</sup>), which resulted in significant improvements in all regional lumbopelvic and global sagittal alignment parameters. Final average post-operative regional sagittal alignments were within acceptable ranges (PT: 13.7<sup>0</sup>; L4-S1 lordosis: 45.9<sup>0</sup>; L1-S1 lordosis: 61.1<sup>0</sup>; PI-LL mismatch: 6.4<sup>0</sup>) as were global alignment metrics (C7-S1 SVA: 1.5; L1PA: 4.3<sup>0</sup>; T4PA: 7.1<sup>0</sup>; T4-L1 PA mismatch: 2.9<sup>0</sup>). At average follow-up of 17 months, no patients had rod breakages or pelvic screw failures. One patient required revision surgery to address proximal junctional kyphosis/failure secondary to overcorrection. Bilateral dual pelvic fixation consisting of traditional iliac screws and osseointegrative S2AI screws to facilitate creation of "super" multi-rod constructs (minimum 6 rods) across L5 PSOs is a safe surgical strategy with promising early clinical results. Larger cohorts from multiple centers with longer follow-up will aid in determining its long-term efficacy.

Medical subject headings

Anatomy