BACKGROUND CONTEXT Poor bone quality and substantive physiologic loads my lead to interbody fixation device subsidence. Severe subsidence can lead to nerve compression and pain that may require revision surgery. Three properties of the interbody device play a role to resist subsidence, footprint (size), end plate contact surface topology and structural modulus (stiffness). Traditionally, it was believed that cages produced with softer materials have low incidence and severity of subsidence and conversely cages with harder materials would lead to stress shielding and high rates and severity of subsidence. More recently, additive manufacturing has enabled the creation of implants with Advanced Structural Designs that decouple material modulus and its perceived impact on subsidence. These new designs focus on architecture and load distribution at the bone implant interface rather than material characteristics. PURPOSE This study is aimed to evaluate subsidence resistance of two commercially available 3D-printed titanium lateral interbody devices of the same size, but with different contact surface topology and structural modulus. STUDY DESIGN/SETTING Mechanical testing using foam blocks. PATIENT SAMPLE N/A OUTCOME MEASURES Subsidence rate of different interbody constructs. METHODS Two 3D-printed titanium lateral interbody devices, one with a truss design that spans throughout the entire construct and contains a snowshoe style bone interface and the other with annular truss design (hollow in the middle) with a metal foam bone interface were used in this study. Both interbody devices were the same dimensions (55mm long, 22mm wide [ant.-to-post.] and 12mm tall).To mimic mechanical properties similar to human bone density (osteoporotic through normal), 5, 10, 15 and 20 PCF SawBone® foam blocks were utilized for testing. To mimic clinical subsidence, the interbody device was placed over the foam block and compressive displacement was applied to push the device into the foam substrate at the rate of 5mm/min. The test was repeated 6 times for each block/implant combination. The subsidence load at 1 and 2mm displacement was collected for each test combination. To calculate the modulus/stiffness, the ratio of load (normalized to contact area) to axial compression rate of the cage-only construct was calculated. Two-way ANOVA with Sidak-Bonferroni Posthoc was used for multiple comparisons and analysis of statistical significance. RESULTS The annular cage design had a stiffness (structural modulus) four times lower than the truss cage design, 176MPa vs 747MPa (p=0.0006).However, the snowshoe effect of the truss contact surface topology resulted in significantly (p CONCLUSIONS The truss cage, despite being structurally stiffer, demonstrated significantly better resistance to subsidence for all foam densities including those that mimic osteoporotic bone compared to the same size annular cage. The subsidence resistance of the truss cage may be due to the distribution of load across a larger cross sectional area at the bone / implant interface (increased line length contact) where the load is uniformly distributed across more of the interbody footprint. The data suggests that the implant's surface contact topology at the endplate plays a greater role than material and structural modulus for resisting subsidence. FDA DEVICE/DRUG STATUS LSTS Lateral Fixation Device (Approved for this indication), Modulus Lateral Fixation Device (Approved for this indication)