Porous Ti-6Al-4V Architectures in Load-Bearing Orthopedic Reconstruction: A Critical Narrative Review of the Translational Gap Across Microstructure, Fatigue, Surface Function, and Clinical Failure Modes.

An aging population and a rising revision burden are increasing demand for bone-compatible load-bearing implants. Because the elastic modulus of conventional Ti-6Al-4V (~110 GPa) exceeds that of cortical bone (7-30 GPa), stress shielding can drive bone resorption and aseptic loosening. Two solution lines have emerged: low-modulus β-type alloys and porous architectures. Focusing on additive manufacturing (AM), this critical narrative review synthesizes the evidence along the axis of clinical failure modes. Materials science has lowered β-Ti's modulus to ~40 GPa in bulk, yet clinical implants rely predominantly on porous conventional Ti-6Al-4V: the low effective modulus (single-digit GPa) comes from architecture, not alloying. These architectures range from porous fixation surfaces on solid acetabular shells to predominantly porous constructs-revision knee cones and sleeves, acetabular augments, and spinal interbody cages. In the acetabular cohorts, where clinical evidence is concentrated, short- to mid-term survivorship is favorable though heterogeneous; revisions were driven mainly by infection and instability, with aseptic loosening low. Two tools are proposed: a synthesis matrix setting laboratory claims alongside clinical evidence for each design parameter, and a 16-item minimum reporting checklist. Applied to the 12 primary series reviewed, the checklist found manufacturing and architecture-verification parameters largely unreported even where clinical outcomes are well documented.