Additively manufactured PLA–bioceramic porous orthopedic implants for biomedical applications: from material-structure co-design to clinical translation

Abstract Porous orthopedic implants are widely studied because they promote osseointegration and reduce stress shielding associated with dense, stiff implants. This review critically examines recent progress in the design and fabrication of additively manufactured porous orthopedic implants, with a focused emphasis on polylactic acid (PLA)–bioceramic systems, particularly hydroxyapatite-, tricalcium phosphate-, and bioactive glass-containing composites. We examine how porosity governs biological outcomes—cell attachment and proliferation, nutrient transport, and bone ingrowth—while simultaneously affecting stiffness, strength, and fatigue resistance. Rather than treating pore size, porosity, and material selection as universally optimal parameters, the review emphasizes that these variables must be interpreted according to implant location, loading environment, degradation profile, and the expected timeline of bone repair. Key structural variables, including pore size, morphology, interconnectivity, and graded architectures, are discussed in the context of meeting load-bearing requirements. Particular attention is given to balancing permeability with mechanical integrity, and to approaches such as ceramic-filled PLA composites and surface modifications that improve bioactivity. Additive manufacturing is presented as an enabling route to couple external geometry with internal architecture, and fused deposition modeling, Stereolithography, and binder jetting are compared with respect to material compatibility, attainable feature resolution, and post-processing needs. Building on these insights, we frame co-design as the joint optimization of material selection and porous structure to maximize overall implant function. Finally, we identify the main barriers to clinical translation, including degradation–healing mismatch, fatigue durability, sterilization, reproducibility of porous architectures, regulatory documentation, and the need for long-term in vivo validation.