Sacro-iliac fixation for treatment of high-grade spondylolisthesis

Sacropelvic fixation

The sacropelvis is not only an anatomically complex region but also a biomechanically unique zone transferring axial weights via the transitional lumbosacral junction and the pelvic girdle to the lower appendicular skeleton. When the sacral instrumentation alone is insufficient to achieve stability and solid arthrodesis across the lumbosacral junction, as in long-segment fusions, high-grade spondylolisthesis, deformity corrections, complex sacral/lumbosacral injuries, and neoplasms, sacropelvic fixation is indicated. Many modern sacropelvic fixation modalities outperform historical modalities, especially the conventionally open and percutaneous iliac and S2-alar-iliac screw (S2AI) fixation techniques. Novel screw insertion technologies such as navigation and robotics and modern screw designs aim to maximize the accuracy of screw placement and minimize complications. This review addresses the anatomy and biomechanics of the sacropelvic region as well as the indications, evolution, advantages, and disadvantages of various past and contemporary techniques of lumbosacral and sacropelvic fixation.

State of the union: a review of lumbar fusion indications and techniques for degenerative spine disease

Lumbar fusion is an accepted and effective technique for the treatment of lumbar degenerative disease. The practice has evolved continually since Albee and Hibbs independently reported the first cases in 1913, and advancements in both technique and patient selection continue through the present day. Clinical and radiological indications for surgery have been tested in trials, and other diagnostic modalities have developed and been studied. Fusion practices have also advanced; instrumentation, surgical approaches, biologics, and more recently, operative planning, have undergone stark changes at a seemingly increasing pace over the last decade. As the general population ages, treatment of degenerative lumbar disease will become a more prevalent-and costlier-issue for surgeons as well as the healthcare system overall. This review will cover the evolution of indications and techniques for fusion in degenerative lumbar disease, with emphasis on the evidence for current practices.

Human versus Robot: A Propensity-Matched Analysis of the Accuracy of Free Hand versus Robotic Guidance for Placement of S2 Alar-Iliac (S2AI) Screws

STUDY DESIGN

Retrospective matched cohort analysis.

OBJECTIVE

To compare the accuracy of S2 alar-iliac (S2AI) screw placement by robotic guidance versus free hand technique.

SUMMARY OF BACKGROUND DATA

Spinopelvic fixation utilizing S2AI screws provides optimal fixation across the lumbosacral junction allowing for solid fusion, especially in long segment fusion constructs. Traditionally, S2AI screw placement has required fluoroscopic guidance for accurate screw placement. Herein, we present the first series comparing a free hand and robotic-guided technique for S2AI screw placement.

METHODS

Sixty-eight consecutive patients who underwent S2AI screw placement by either a free hand or robotic technique between 2015 and 2016 were reviewed. Propensity score-matching was utilized to control for preoperative characteristic imbalances. Screw position and accuracy were evaluated using three-dimensional manipulation of computed tomography scan reconstructions from intraoperative O-arm imaging.

RESULTS

A total of 51 patients (105 screws) were matched, 28 (59 screws) in the free hand group (FHG) and 23 (46 screws) in the robot group (RG). The mean age in the FHG and RG were 57.9 ± 14.6 years and 61.6 ± 12.0 years (P = 0.342), respectively. The average caudal angle in the sagittal plane was significantly larger in the RG (31.0 ± 10.0° vs. 25.7 ± 8.8°, P = 0.005). There was no difference between the FHG and RG in the horizontal angle, measured in the axial plane using the posterior superior iliac spine (PSIS) as a reference (41.1 ± 8.1° vs. 42.8 ± 6.6°, P = 0.225), or the S2AI to S1 screw angle (9.4 ± 7.0° vs. 11.3 ± 9.9°, P = 0.256), respectively. There was no difference in the overall accuracy between FHG and RG (94.9% vs. 97.8%, P = 0.630). Additionally, there were no significant intraoperative neurovascular or visceral complications associated with S2AI screw placement.

CONCLUSION

Free hand and robotic-guided S2AI screw placement both prove to be safe, accurate, and reliable techniques for achieving spinopelvic fixation.

LEVEL OF EVIDENCE

3.

Pelvic Fixation in Adult and Pediatric Spine Surgery: Historical Perspective, Indications, and Techniques: AAOS Exhibit Selection

Achieving solid osseous fusion across the lumbosacral junction has historically been, and continues to be, a challenge in spine surgery. Robust pelvic fixation plays an integral role in achieving this goal. The goals of this review are to describe the history of and indications for spinopelvic fixation, examine conventional spinopelvic fixation techniques, and review the newer S2-alar-iliac technique and its outcomes in adult and pediatric patients with spinal deformity. Since the introduction of Harrington rods in the 1960s, spinal instrumentation has evolved substantially. Indications for spinopelvic fixation as a means to achieve lumbosacral arthrodesis include a long arthrodesis (five or more vertebral levels) or use of three-column osteotomies in the lower thoracic or lumbar spine, surgical treatment of high-grade spondylolisthesis, and correction of lumbar deformity and pelvic obliquity. A variety of techniques have been described over the years, including Galveston iliac rods, Jackson intrasacral rods, the Kostuik transiliac bar, iliac screws, and S2-alar-iliac screws. Modern iliac screws and S2-alar-iliac screws are associated with relatively low rates of pseudarthrosis. S2-alar-iliac screws have the advantages of less implant prominence and inline placement with proximal spinal anchors. Collectively, these techniques provide powerful methods for obtaining control of the pelvis in facilitating lumbosacral arthrodesis.

Sacropelvic fixation: techniques and complications

STUDY DESIGN

Literature-based topic review.

OBJECTIVE

To review the indications and techniques for different sacropelvic fixation methods and to outline important associated complications.

SUMMARY OF BACKGROUND DATA

Despite all the advances and new developments in spinal instrumentation techniques, fixation at the lumbosacral junction continues to be one of the important challenges to spine surgeons. The poor bone quality of the sacrum, the complex regional anatomy, and the tremendous biomechanical forces at the lumbosacral junction contribute to the high rates of instrumentation-related problems. Although many techniques for sacropelvic fixation have been attempted, only a few are still widely used because of the high rate of complications associated with some of those techniques.

METHODS

Review of literature and expert opinion.

CONCLUSION

There are many indications for sacropelvic fixation. Long fusions to the sacrum are the most common reasons for extending the instrumentation to the pelvis. Spinal surgeons performing complex spinal reconstruction should be familiar with the currently available techniques, including their potential risks and complications. Surgical treatment decisions should be based on an individual patient's anatomy and abnormalities, and on the surgeon's experience.