Sacropelvic Fixation. Ahmet Alanay M.D. Professor. Acıbadem Maslak Hospital Comprehensive Spine Center Istanbul TURKEY

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1 Sacropelvic Fixation Ahmet Alanay M.D. Professor Acıbadem Maslak Hospital Comprehensive Spine Center Istanbul TURKEY

2 Conflict of Interest Grant Depuy & Synthes

3 Definition Sacropelvic fixation Long spinal fusions to the sacrum Secure fixation to resist the strong flexion moments and cantilever forces Multiple techniques Galveston rod Iliac screws S2 alar iliac (S2AI) technique

4 Indications Long spinal fusions Lumbar scoliosis in adults Paralytic scoliosis High-grade spondylolisthesis Flat back syndrome requiring corrective osteotomy Correction of pelvic obliquity Other disorders Sacrectomy Sacral fracture

5 Anatomy Biomechanical strength is higher at Zone 3 Zone 3 allows the farthest anterior fixation to pivot point Structures at greater sciatic foramen at risk of damage

6 High incidence of pseudo Fusion mass acts as a long level arm transmitting flexion, extension and torsional forces Density of bone in sacrum is poor Lumbosacral pivot point The farther anterior this point, the more stable the construct Biomechanics

7 Preoperative planning Pts who had prior bone taken may not be candidates A C-arm is necessary Pts with pelvic obliquity and rotation may have significant differences between 2 sides Pts with significant osteoporosis may require 10 mm screws

8 Positioning & Approach Radiolucent table is mandatory Distal draping of the gluteal folds right after positioning may help prevent contamination Approach in general is extension of midline incision Galveston, iliac screw S2AI

9 Galveston Technique Inserted through PSIS Special bending is needed Advantages Less prominent No need for cross connectors Disadvantages Difficulty in shaping Does not allow iliac bone graft harvesting

10 Iliac Screw Technique Insertion point 1 cm distal of PSIS The bulkiness of PSIS is resected to decrease the screw profile The path is 25 degrees lateral to midsagittal plane and 30 to 35 degrees caudal to the transverse plane toward the ASIS

over the table and tilting 30-40 degrees

11 Iliac Screw Technique Fluoroscopic teardrop view Rolling C-arm degrees over the table and tilting degrees cephalad, which creates overlap of ASIS and PSIS

12 Iliac Screw Technique Screw size 7 to 8 mm, length 70 to 80 mm Screws are than attached to longitudinal rods

13 Iliac Screw Technique Advantages Familiarity with the technique No need for rod shaping Disadvantages Need for cross connectors High profile Does not allow iliac bone graft harvesting

14 S2AI Technique Should be placed after S1 screw Starting point located in line with the lateral edge of S1 foramen and 5 to 10 mm distal to the S1 foramen Trajectory 40 degrees lateral angulation in transverse plane and 40 degrees of caudal angulation in sagittal plane toward the ASIS

15 S2AI Technique 2.5 mm drill bit is used to tap the SI joint Distance roughly 30 to 45 mm Drill bit is replaced with 3.2 in order to reduce reduce risk of breakage in harder bone and advanced for 80 to 90 mm Screw sizes 8 to 10 mm by 80 to 100 mm

16 S2AI Technique Advantages No need for cross connectors Longer and larger diameter screws Penetration of 2 cortices Partly allows iliac bone graft harvesting Disadvantages Technical difficulty and unfamiliarity Penetration of SI joints

17 58Y F ADULT IS

19 Multilevel SPO

21 75 y, f myelopathy, difficulty in walking, osteoporosis, T8-9, T12-L1 hard disk, lumbar spinal stenosis

22 PEARLS FOR ILIAC FIXATION Indications Long spinal fusions to the sacrum are the most common indication for sacropelvic fixation. Teardrop fluoroscopic view The teardrop is created by the overlap of the AIS and PSIS and represents a bony canal through which the pelvic fixation may be safely placed. Damage to surrounding soft tissues Structures in the sciatic notch are at risk, Minimized by verifying a bony endpoint with a blunt probe prior to screw placement. Implant prominence Most common reason for revision. Minimized by creating a notch prior to placement of the iliac screw, by burying the screw beyond the PSIS, by choosing a medial starting point for the screw, or by using the S2AI technique. Instrumentation loosening Minimize by using largest acceptable diameter screw. Addition of an anterior fusion increases construct stability.

23 THANK YOU

Pelvic Fixation. Disclosures 5/19/2017. Rationale for Lumbo-pelvic Fixation

Pelvic Fixation. Disclosures 5/19/2017. Rationale for Lumbo-pelvic Fixation Pelvic Fixation Joseph M Zavatsky, MD Spine & Scoliosis Specialists Tampa, FL Disclosures Consultant - DePuy Synthes Spine, Zimmer Biomet, Amendia, Stryker Stock - Innovative Surgical Solutions, Vivex