Pure Titanium and Titanium Polyetheretherketone Cages versus Polyetheretherketone for Transforaminal Lumbar Interbody Fusion: A Systematic Review and Mixed-Effect Meta-Analysis

Introduction: Transforaminal lumbar interbody fusion (TLIF) is a standard surgical intervention for many lumbar spinal disorders. Polyetheretherketone (PEEK), pure titanium (Ti), and titanium-coated PEEK (TiPEEK) cages have been thought to impact patient outcomes following TLIF due to differences in material properties affecting bone-implant integration and fusion. Pure Ti and TiPEEK cages aim to enhance bioactivity, potentially improving fusion outcomes compared to more inert PEEK cages. We, therefore, sought to assess the efficacy and safety of pure Ti or TiPEEK versus PEEK cages in TLIF.

Methods: A systematic review was conducted following PRISMA guidelines across four major databases (PubMed, EMBASE, CENTRAL, and Web of Science) including articles published up to October 4, 2024. Only publications that compared the effectiveness of pure Ti or TiPEEK versus PEEK cages were included. Statistical meta-analysis was performed using R, utilizing a mixed-effects model to account for multiple time points and incorporating the Mantel–Haenszel method.

Results: From the initial 929 studies identified, 12 met the inclusion criteria. Compared to PEEK cages, patients who received pure Ti cages had a significant improvement in disc height (effect size [ES]: 0.87, p< 0.01) and showed a trend toward better functional outcomes as measured by the Oswestry Disability Index (ES: 0.35, p=0.05). TiPEEK cages demonstrated a significant reduction in the risk of cage subsidence (ES: 0.77, p=0.04) and improved disc height (ES: 2.37, p< 0.01) compared to PEEK cages. Visual analog scale (VAS) low back pain scores for patients with TiPEEK cages were also significantly lower compared to those with PEEK cages (ES: -0.24, p< 0.01).

Conclusion : Our findings emphasize the advantages of both pure Ti and TiPEEK cages over PEEK cages in terms of disc height and pain outcomes. Pure Ti cages provided significant gains in disc height. TiPEEK cages, meanwhile, significantly reduced the risk of cage subsidence, enhanced disc height, and lowered VAS low back pain scores, highlighting their structural and functional benefits. These results suggest that pure Ti and TiPEEK cages are valuable alternatives to PEEK cages, potentially leading to better patient outcomes following TLIF.