193. Biomimetic 3D-printed titanium-alloy interbody spacers demonstrate uniform bone growth over 12 weeks

Abstract

BACKGROUND CONTEXT A primary clinical outcome of interbody fusion surgery is achievement of bony fusion. Polyetheretherkeytone (PEEK) and titanium-alloy (TAV) have been used for years as interbody implant materials, although each material has unique drawbacks related to visualization, stiffness, and biocompatibility. Due to advancements in 3D printing technology, titanium-alloy (TAV) interbody spacers can be made with complex and innovative designs, such as a porous structure that mimics the architecture of trabecular bone. Implants with a microscale surface roughness and a biomimetic, porous structure may promote formation of new bone. A uniform rate of bone formation during healing may lead to optimized fusion. PURPOSE The purpose of this study was to compare bone growth rate (BGR) following lateral lumbar interbody fusion (LLIF) between interbody fusion devices made from polyetheretherketone (PEEK), titanium-alloy (TAV), and 3D-printed biomimetic titanium-alloy (3DP) interbody implants in an ovine model. STUDY DESIGN/SETTING In Vivo animal study. PATIENT SAMPLE N/A OUTCOME MEASURES Microcomputed tomography was used to quantify bone volume (BV) and the BGR within the spacers at three time points. Postoperative time points were 6 and 12 weeks. BV at the initial postoperative time point (0 weeks) was also quantified by implanting cadaver sheep with autograft bone packed spacers (n=4 levels per group). METHODS Eighteen sheep underwent a two-level (L2–L3 and L4–L5) LLIF using PEEK, TAV or 3DP spacers (n=6 levels per group per time point). Animals were sacrificed at 6 and 12 weeks postoperatively. BGR was calculated for each treatment group between the three time points. RESULTS The 3DP-treated group demonstrated a more consistent BGR over 12 weeks compared to PEEK and TAV groups. The BGR for the 3DP group was 10.6 mm3/week and 9.6 mm3/week from 0 to 6 weeks and 6 to 12 weeks, respectively. Bone growth in PEEK and TAV groups was delayed, evidenced by not surpassing the remodeling phase until after 6 weeks. Additionally, PEEK and TAV groups had an inconsistent BGR between early and late time intervals (PEEK: 1.5 and 17.0mm3/week, respectively; TAV: -2.1 and 17.7mm3/week, respectively). CONCLUSIONS This study demonstrated porous, biomimetic 3DP TAV interbody spacers led to robust intervertebral fusion. 3DP implants facilitated uniform bone growth through the spacers over 12 weeks, evidenced by lower bone volume observed with PEEK and TAV implants at 6 weeks. This data suggests that porous, biomimetic 3DP spacers are a favorable alternative to PEEK and TAV for interbody fusion, promoting a uniform rate of bone growth over 12 weeks. FDA DEVICE/DRUG STATUS HEDRON (Globus Medical) (Approved for this indication)