Pelvic Fixation Techniques in Spinal Deformity Surgery

Pelvic fixation serves as a cornerstone in the surgical management of complex spinal deformities, providing distal anchorage to control pelvic obliquity and restore global balance. Techniques have evolved from iliac screw constructs to more contemporary sacral‐alar‐iliac trajectories, dual‐screw strategies and novel implant geometries. The primary objectives are to optimise coronal and sagittal realignment, distribute biomechanical loads across the lumbosacral junction and reduce the risk of caudal implant failure. Patient-specific factors—such as pelvic incidence, bone quality and the nature of deforming pathology—guide technique selection. Anatomical constraints of the posterior pelvis, potential for neurovascular injury and implant prominence are countered by precise trajectory planning and intraoperative imaging. Outcomes are assessed in terms of radiographic correction, durability of fusion, incidence of hardware loosening and patient-reported quality of life.

Research from Nature Portfolio

Recent studies have assessed the impact of pelvic fixation in neuromuscular scoliosis where pelvic obliquity often exceeds 15°. A multicentre analysis compared patients instrumented to the ilium via iliac screws with those stopping at S1 or L5 over a two-year follow-up. Despite variations in distal fixation levels, rates of deformity correction, loss of correction and clinical outcomes—including quality of life measures—showed no significant differences between groups. These findings suggest that iliac fixation may not confer additional radiological or functional benefit in certain neuromuscular populations, prompting reassessment of routine extension to the pelvis when pelvic obliquity alone dictates fusion levels.

Research from all publishers

Biomechanical finite element analysis has illuminated the comparative merits of S2-alar-iliac and traditional iliac screws. Models using various screw lengths and head angles demonstrated that a 90 mm S2-alar-iliac screw with a 15° polyaxial head angle minimises peak stresses on both implant and adjacent bone, indicating a lower risk of mechanical failure. Clinical series have explored bilateral dual iliac screws augmented by S1 pedicle fixation in adult deformity correction. Two-year postoperative assessment revealed low rates of screw loosening and satisfactory maintenance of sagittal and coronal parameters. A retrospective cohort comparing iliac screw and S2-alar-iliac constructs in long-segment adult spinal deformity demonstrated that iliac screws allow greater restoration of lumbar lordosis but may be associated with increased sacroiliac joint pain and hardware complications, highlighting the trade-off between lordotic correction and implant-related morbidity.

Pelvic Fixation Techniques in Spinal Deformity Surgery publication trend

The graph below shows the total number of articles in pelvic fixation techniques in spinal deformity surgery across all publications each year (not limited to Nature Index journals).

Technical terms

Pelvic obliquity: Angular tilt of the pelvis in the coronal plane relative to the horizontal axis.

Iliac screw: Pedicle-style screw placed through the posterior superior iliac crest into the ilium for distal spinal fixation.

S2-alar-iliac (S2AI) screw: Screw trajectory originating in the sacral ala crossing into the ilium, designed to reduce prominence and optimise biomechanical loading.

Spinopelvic fixation: Combined instrumentation of the lumbar or thoracolumbar spine and the pelvis to achieve stabilisation across the lumbosacral junction.

References

1. Clinical and radiological efficacy of spino-pelvic fixation in the treatment of neuromuscular scoliosis. Scientific Reports (2023).
2. Effect of the screw type (S2-alar-iliac and iliac), screw length, and screw head angle on the risk of screw and adjacent bone failures after a spinopelvic fixation technique: A finite element analysis. PLOS ONE (2018).
3. Bilateral dual iliac screws in spinal deformity correction surgery. Journal of Orthopaedic Surgery and Research (2018).
4. Use of iliac screw associated with more correction of lumbar lordosis than S2-alar-iliac screw for adult spinal deformity. BMC Musculoskeletal Disorders (2021).