3D-Printed Porous Titanium Cages in Lumbar Interbody Fusion.

Lumbar degenerative disease is one of the most common indications for spinal surgery, and lumbar interbody fusion (LIF) remains a central technique in its management. The performance of an interbody fusion cage largely depends on its material composition and structural design, which influence segmental stability and the quality of bony fusion. This review summarizes the material characteristics, biomechanical rationale, biological behavior, and clinical applications of three-dimensional-printed porous titanium (3D-pTi) interbody cages. Advances in additive manufacturing enable precise control of pore size, porosity, and lattice architecture, allowing the elastic modulus of 3D-pTi cages to be tuned to more closely approximate that of cancellous bone. These optimizations may improve load transfer, reduce stress shielding, and promote a favorable environment for osseointegration. The interconnected porous structure and roughened surface support osteoblast adhesion, bone ingrowth, and early vascularization. Preclinical studies consistently demonstrate that 3D-pTi cages provide higher bone-implant contact and bone volume fraction compared with solid titanium and polyetheretherketone (PEEK) implants. Early clinical findings across transforaminal lumbar interbody fusion (TLIF), lateral lumbar interbody fusion (LLIF), and anterior lumbar interbody fusion (ALIF) suggest that 3D-pTi cages can achieve high radiographic fusion rates, maintain intervertebral height, and exhibit an acceptable short-term safety profile. However, existing studies are limited by small sample sizes, methodological heterogeneity, and relatively short follow-up durations. Overall, 3D-pTi cages represent a promising biomechanically compatible and osteoconductive option for LIF in degenerative conditions. Nevertheless, their long-term clinical benefits, cost-effectiveness, and optimal indications require further investigation in rigorously designed studies.