Biomaterials and biomechanical design of distal weight-bearing implants: Computational modeling, biomaterial...

Distal Weight-Bearing Implants (DWBIs) represent a clinically emerging class of load-bearing medical devices in which biomaterial design, surface architecture, and biomechanical performance are tightly coupled. Their success depends not only on restoring distal support in transfemoral rehabilitation, but also on the ability of metallic, ceramic, and composite biomaterial interfaces to sustain cyclic loading while promoting durable bone-implant integration. However, distal support also changes bending moments, shear stresses, micromotion, coating durability, and biological demands at the bone-implant interface. This systematic review synthesizes DWBI concepts, geometry optimization, finite element analysis with gait-phase loading, Functionally Graded Materials (FGMs), graded Ti-HAp (hydroxyapatite) architectures, in-vivo osseointegration evidence, and clinical translation pathways. A quantitative trend analysis was performed on 34 direct-contribution papers and 32 empirical studies to assess trends, validation depth, and translation readiness. However, more than half of the empirical evidence remained at the bench or simulation level, while animal and human/clinical studies formed a smaller validation layer. HAp-centered surface or bulk material engineering represented a substantial share of the corpus; however, evidence for graded Ti-HAp/FGM architectures was derived predominantly from non-DWBI biomaterial and mechanistic analog studies, supporting mechanistic plausibility rather than DWBI-specific validation. Mechanistically, DWBI should be interpreted as an integrated biomaterial-mechanical system linking macro-geometry, metallic/ceramic surface architecture, graded Ti-HAp interfaces, gait-phase loading, tribology/corrosion behavior, in-vivo fixation, and clinical workflow. Translation will require patient-realistic loading conditions, validated finite element analysis workflows, device-level fatigue and coating-integrity testing, standardized in-vivo endpoints, harmonized rehabilitation protocols, and registry-supported clinical follow-up linking mechanical plausibility to durable biological fixation and patient-level benefit.