Lumbar Fusion with Micro- & Nano-textured, 3D Printed Porous Titanium versus PEEK Interbody Cages: A Single-blinded, Randomized Controlled Trial

Introduction: Current literature is relatively limited regarding studies directly comparing 3D-printed porous titanium (3DPPT) and PEEK for lumbar interbody fusion. A micro- & nano-textured 3DPPT interbody is a promising solution combating the limitations of PEEK (biocompatibility, osteointegration, pseudoarthrosis) and conventional titanium (subsidence, stress shielding). We aim to assess its safety and efficacy via early radiological outcomes in transforaminal lumbar interbody fusion (TLIF) compared to PEEK.

Methods: We conducted a single-blinded prospective, randomized controlled trial comparing 1-2 level TLIF with a micro- & nano-textured 3DPPT versus a PEEK cage from 11/2021-5/2023. Interbody fusion was assessed on CT at 6 months according to Brantigan and Steffee method, as modified to describe the Fraser definition of locked pseudoarthrosis [(BSF) scale]. Primary outcome was radiographic fusion at 6 months. An independent radiographic analysis was performed. Data analysis was performed using unpaired t test, χ2, Fisher’s exact tests, and ANOVA, as appropriate.

Results: Amongst 18 patients with 25 interbody levels implanted, 10 3DPPT and 15 PEEK cages were implanted. 3DPPT levels had a significantly higher rate of successful fusion (BSF-3) at 6 months compared with PEEK (100% vs. 0.0%, p< 0.001). Initial study protocol included 70 total patients. However, the study was ended early given the significance of the results on interim analysis. There was no significant difference in baseline demographics or comorbidities. There was also no significant difference in lumbar pathologies, level of fusion (p=1), number of fused levels (p=1), length of hospital stay (p=0.281), surgery duration (p=0.155), estimated blood loss (p=0.842), complications (p=1), or reoperations (p=1).

Conclusion : The rate of successful lumbar interbody fusion at 6 months was significantly higher in 3DPPT levels compared to PEEK. 3DPPT may accelerate the rate and quality of bony fusion and is associated with a low subsidence and reoperation rates. Additional studies are needed to further delineate the impact of these radiographical findings on long-term clinical outcomes. Innovations in 3D printing engineering and computational modeling have the potential to enable patient-specific implants customized to bone density and surface morphology.