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

Purpose 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. Methods 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. Results 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 0 ± 3.2 0 (range, 30–39 0 ), 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 0 ; L4-S1 lordosis: 45.9 0 ; L1-S1 lordosis: 61.1 0 ; PI-LL mismatch: 6.4 0 ) as were global alignment metrics (C7-S1 SVA: 1.5; L1PA: 4.3 0 ; T4PA: 7.1 0 ; T4-L1 PA mismatch: 2.9 0 ). 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. Conclusions 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.