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What Is Sacropelvic Fixation?

Sacropelvic fixation is a spinal stabilization technique that anchors a lumbosacral fusion construct to the pelvis. It is commonly performed with traditional iliac screws or lower-profile S2 alar-iliac screws, often abbreviated S2AI screws. Pelvic fixation creates a strong distal foundation when the sacrum alone is unlikely to provide enough support for a long or mechanically demanding fusion. The implants are connected to rods extending from the lumbar or thoracolumbar spine so the construct can resist forces across the lumbosacral junction while fusion develops.

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What Is Sacropelvic Fixation?

Sacropelvic fixation is a spinal stabilization technique that anchors a lumbosacral fusion construct to the pelvis. It is commonly performed with traditional iliac screws or lower-profile S2 alar-iliac screws, often abbreviated S2AI screws. Pelvic fixation creates a strong distal foundation when the sacrum alone is unlikely to provide enough support for a long or mechanically demanding fusion. The implants are connected to rods extending from the lumbar or thoracolumbar spine so the construct can resist forces across the lumbosacral junction while fusion develops.

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Why Is Sacropelvic Fixation Performed?

The technique is used for long spinal fusions to the sacrum, adult or pediatric deformity correction, high-grade spondylolisthesis, three-column osteotomy, vertebral column resection, sacral fracture, tumor, infection, or revision of failed lumbosacral fusion. It can also be added when poor sacral bone quality or major pelvic obliquity makes distal fixation less reliable. The goal is to reduce stress on S1 screws and improve the mechanical environment for fusion at L5-S1 and the sacrum. The choice between iliac and S2AI fixation depends on anatomy, prior surgery, deformity, implant strategy, and surgeon preference.

How Is Sacropelvic Fixation Performed?

After the lumbosacral spine is exposed, the surgeon places screws from the sacral or posterior pelvic region into strong bone of the ilium. Traditional iliac screws begin near the posterior iliac crest, while S2AI screws start more medially near the second sacral level and cross the sacroiliac joint into the ilium. Imaging, navigation, or robotic guidance can be used to confirm the screw trajectory and avoid the hip joint, sciatic notch, and nearby neurovascular structures. The pelvic screws are connected to the spinal rods and combined with bone graft to support fusion across the lumbosacral junction.

What Is Recovery Like After Sacropelvic Fixation?

Recovery usually follows the course of the larger spinal fusion or deformity operation in which pelvic fixation was placed. Patients begin walking and rehabilitation as neurologic status, pain control, and the overall reconstruction allow. Bending, lifting, twisting, and high-impact activity are restricted while the lumbosacral fusion develops over several months. Follow-up imaging monitors screw position, rod integrity, alignment, fusion at L5-S1, and any signs of loosening or mechanical failure.

What Are the Risks and Complications?

Possible complications include infection, wound breakdown, screw loosening, rod or screw fracture, pseudarthrosis, sacroiliac pain, and the need for revision surgery. Traditional iliac screws can be prominent beneath the skin and can cause local pain or wound problems. Recent meta-analyses report lower rates of symptomatic prominence, wound complications, and revision with S2AI screws than with traditional iliac screws in adult spinal deformity populations. Malpositioned pelvic screws can also injure nearby nerves, blood vessels, pelvic structures, or the hip joint.

Frequently Asked Questions About Sacropelvic Fixation

What are the main types of sacropelvic fixation?

The two most common modern techniques are traditional iliac screws and S2 alar-iliac screws, which anchor a spinal construct into the pelvis through different trajectories.

Why is pelvic fixation added to a long spinal fusion?

It provides a stronger distal anchor and reduces mechanical stress at the lumbosacral junction, where long constructs have a high risk of nonunion or hardware failure.

What is an S2AI screw?

An S2AI screw starts near the second sacral level and crosses the sacroiliac joint into the ilium, creating a low-profile pelvic anchor that aligns well with spinal rods.

Can sacropelvic fixation hardware fail?

Yes. Loosening, rod or screw breakage, pseudarthrosis, and symptomatic hardware can occur and can require revision surgery.

References

Direct Iliac Screw vs Sacral-2-Alar-Iliac Screws Technique for Sacropelvic Fixation: Technical Nuances and a Review of the Literature. PubMed. https://pubmed.ncbi.nlm.nih.gov/37055178/. Date Accessed September 11, 2026.

Sacropelvic Fixation: A Comprehensive Review. PubMed. https://pubmed.ncbi.nlm.nih.gov/31202365/. Date Accessed September 11, 2026.

Sacropelvic Fixation for Adult Deformity Surgery Comparing Iliac Screw and Sacral 2 Alar-Iliac Screw Fixation: Systematic Review and Updated Meta-Analysis. PubMed. https://pubmed.ncbi.nlm.nih.gov/38171313/. Date Accessed September 11, 2026.

Sacropelvic Fixation: When, Why, How? PubMed. https://pubmed.ncbi.nlm.nih.gov/29933806/. Date Accessed September 11, 2026.

Spinopelvic fixation failure in the adult spinal deformity population: systematic review and meta-analysis. PubMed. https://pubmed.ncbi.nlm.nih.gov/38619634/. Date Accessed September 11, 2026.