Nano-hydroxyapatite/Polylactic Acid Composite Scaffolds for Bone Tissue Regeneration: Preparation, Modification, and Clinical Translation Challenges

Bone defect repair has long been a core challenge in clinical orthopedics and maxillofacial surgery. Nano-hydroxyapatite/polylactic acid (nHA/PLA) composite scaffolds, which combine the processability of polylactic acid with the biological activity of hydroxyapatite, are a highly regarded material system in the field of bone tissue engineering. This paper analyzes from four levels: material preparation, functional modification, bioperformance and transformation bottleneck, systematically reviews the applicable boundaries of mainstream preparation techniques such as 3D printing and electrospinning, and compares the advantages and disadvantages of three modification strategies: ion doping, active factor loading, and multi- component compounding. The study found that nHA/PLA composite scaffolds have accumulated sufficient positive evidence in non-load-bearing bone repair, but problems such as nHA dispersion, degradation-regeneration matching, and the lack of load-bearing bone application data still restrict their clinical translation. In particular, there is a lack of consensus on the dynamic equilibrium of acid production from PLA degradation and alkaline neutralization of nHA, as well as the immune-osteogenic coupling mechanism. Future research will continue to advance in three areas: multi-scale design, immune regulation, and large animal evaluation.