Low Profile Percutaneous Iliac Fixation

Presented at SMISS Annual Forum 2016
By Chun-Po Yen MD
With Juan S. Uribe MD, FACS, Puya Alikhani MD, Andrew Vivas MD, Jason Paluzzi , Konrad Bach ,

Disclosures: Chun-Po Yen MD None Juan Uribe MD, FACS A; Nuvasive. B; Nuvasive. C; Nuvasive. D; Nuvasive. F; Nuvasive, Puya Alikhani MD None, Andrew Vivas MD None, Jason Paluzzi None, Konrad Bach None,

Introduction

Placement of iliac screws provides augmented stability for long fusion constructs in patients undergoing deformity spine surgery. The traditional starting point at the posterior superior iliac spine (PSIS) poses difficulty for rod placement when the posterior instrumentation is performed in a minimally invasive fashion. Additionally, prominence can become a source of discomfort or skin breakdown. 

Aims/Objectives

The authors describe a novel iliac screw starting point as a method of pelvic fixation and compare this technique with insertion from the PSIS. 

Methods

A fluoroscopic outlet view was taken to localize the S1 and S2 foramen. A 2-cm midline incision at the level midway between S1/S2 foramen was made. A Jamshidi needle was docked at the starting point chosen at the iliac tuberosity immediately dorsal to the sacroiliac joint (roughly between PSIS and posterior inferior iliac spine). The trajectory aims towards the acetabulum cap just above sciatic notch. The needle was advanced towards the great trochanter while remained in the lower portion of the “teardrop” on the oblique obturator/outlet view. The inlet view can be checked from time to time to verify that the needle traversed close but superior to the sciatic notch. A guide-wire was introduced through the needle. An appropriate sized cannulated tap was used over the guide-wire to prepare the pathway of the screw. 8.5 mm-diameter and 80-100 mm-length iliac screws were placed to maximize cortical bone purchase between the inner and outer iliac tablets and engage the roof of sciatic notch. 

Results

Five patients undergoing thoracolumbosacral or lumbosacral instrumented fusion had iliac screws placement using the new entry point. The rods were placed subfasically and none of them required offset connectors. All screws were adequately buried under the iliac wings without prominence of the hardware. Short-term follow-up of these patients demonstrates no evidence of hardware failure. 

Conclusions

The described technique offers an alternative entry point that provides ease for rod placement in a minimally invasive fashion given the entry point lining up with pedicle screw entry points at the lumbosacral segment. Placement of the iliac screws in the recess between posterior iliac wing and the sacrum avoids hardware prominence. Further biomechanical studies are needed to test the fixation strength. Longer follow-up and a larger series are required to show the safety and efficacy of this technique.