Biodegradability, biocompatibility and toxicity assessment of PLA/PCL/hydroxyapatite bioscrew derived from green mussel shells

Bioscrew implants are widely used in anterior cruciate ligament (ACL) reconstruction, and hydroxyapatite (HA) remains a preferred biomaterial for bone grafting due to its osteoconductive and biocompatible properties. This study evaluated the biodegradability, biocompatibility, and potential liver and kidney effects of a bioscrew composed of polylactic acid (PLA), polycaprolactone (PCL), and HA derived from green mussel shells ( Perna viridis ) as a sustainable implant alternative. A true experimental, post-test-only control-group design was used with 40 male New Zealand rabbits randomly assigned to 8 groups. Four intervention groups received PLA85/PCL15/HA5 bioscrews, while four control groups received empty defects. Animals were observed at weeks 2, 4, 6, and 12, representing key phases of bone healing. Biocompatibility, degradation behavior, and liver and kidney organ responses were assessed using blood biomarkers and histopathology in accordance with ISO 10993-6 criteria. Data were analyzed with the Kruskal–Wallis and Mann–Whitney U tests; p < 0.05 was considered statistically significant. Histological evaluation showed progressively improved bone integration from week 4 onward, marked by neovascularization, cellular proliferation, and medullary bone formation along the implant site. The bioscrews exhibited gradual and controlled degradation, characterized by surface erosion and macrophage activity without excessive inflammation. Liver and kidney histology, as well as biochemical parameters, remained within normal limits, suggesting no detectable toxicity within these organs. These findings indicate that PLA85/PCL15/HA5 bioscrews incorporating mussel-shell-derived HA possess favorable biocompatibility, predictable biodegradation, and acceptable liver and kidney safety, supporting their promise as an environmentally sustainable orthopedic implant candidate.