•Sacroiliac joint dysfunction is implicated in 15-30% of low back pain.1

•Implant site, design, interface with bone, and approach differentiate primary (lateral, posterolateral, posterior) and secondary (anterior, posteromedial) arthrodesis techniques. 2-5

•Currently no comparative cadaveric study of fixation efficacy, invasiveness, and fusion potential. 4-7

•Assess motion reduction, fusion area, and volume of bone removed of a novel posterior integrated transfixation cage system (Fig. 1) and compare its side-by-side performance to the posterolateral cylindrical threaded implant, and to published data on the lateral triangular rod system within the same model.8

•19 cadaveric sacroiliac joints: 6-posterior, 6-posterolateral (50±16 years old, -1.1±1.1 L4 T-Score), and 7-lateral (59±6 years old, 0.8±0.2 L4 T-score).

•Multidirectional pure moment bending tests performed in intact, destabilized, and treated conditions in single-leg stance

•Relative motion between the sacrum and ilium was measured during flexion-extension (FE), axial rotation (AR), and lateral bending (LB) applied moments (0-7.5 Nm).

•Volume of bone removed and surface area available for fusion was calculated using computational models (Fig. 2) that were reconstructed using fine-cut CT scans and manufacturer surgical technique guides.

•Motion Reduction (Fig. 3)

•Posterior cage reduced FE and AR while lateral rods reduced only FE significantly (p<0.05).

•Posterior cage was equivalent to lateral triangular rods (p>0.58)

•Posterolateral threaded implant less effective than both posterior cage and lateral rods in FE (6%±3% vs. 37%±10% & 33%±11%)

•Fusion Area (Fig. 4)

•Posterior cage decorticated the most surface area (p<0.05)

•Bone Removed (Fig. 5)

•Posterior cage removed the least bone stock (p<0.05)

CONCLUSIONS