Comparison of Osseointegration in 3d-printed Hexanium Titanium Cages and Peek cervical Cages: In-vivo Ovine Cervical Fusion Model

Introduction: The purpose of this study was to evaluate intervertebral cage migration and bony ingrowth in 3D-printed additive manufacturing titanium cages with hexagonal geometry in the cage walls, compared to traditional PEEK anterior cervical cages, using an in-vivo ovine model. This study investigates the potential benefits of 3D-printed titanium cages in terms of bone integration and stability, which may be critical for improving cervical fusion outcomes.

Methods: A comparative animal study was conducted in eight ovine cervical spines. Both 3D-printed titanium and PEEK interbody cages were implanted without fixation. After 8 weeks, animals underwent full-body CT scans to evaluate cage position. At 12 weeks, a micro-CT scan and histological analysis were performed to qualitatively assess: (i) the cage position, (ii) the ratio of bone ingrowth inside the central window of the cage in terms of area and volume, and (iii) the osseointegration within the 3D-printed titanium cages, particularly focusing on the complex geometry with hexagonal wall patterns.

Results: In the central window of the cages, the mean percentage of bone area/total area for the PEEK and 3D-printed titanium groups was 3.79 ± 7.26% and 10.46 ± 8.52%, respectively (p = 0.086). The mean percentage of bone volume/total volume for PEEK and 3D-printed titanium groups was 7.83 ± 6.65% and 20.53 ± 14.56%, respectively (p = 0.018). Histological results aligned with the micro-CT findings, showing more bone ingrowth in the titanium group. Implant migration was more frequent in PEEK cages (87.5%) compared to 3D-printed titanium cages (37.5%).

Conclusion : 3D-printed titanium cages demonstrated significantly increased bone formation in an ovine model, with promising osseointegration in the hexagonal geometry. This early bone growth may contribute to reduced cage migration, highlighting the potential advantages of 3D-printed titanium cages over traditional PEEK implants. However, further studies are required to confirm these preliminary findings and assess long-term clinical relevance.