Hybrid resorbable anchors/biomolecule-eluting nanofibers for enhanced pedicle screw fixation

Pedicle screw loosening remains a challenge for surgeons and patients. We propose using hybrid resorbable anchors and drug/biomolecule-eluting nanofibers to enhance the bone fixation of pedicle screws. Polylactide (PLA) anchors with various designs were fabricated using additive manufacturing, while simvastatin- and bone morphogenetic protein-2 (BMP-2)-loaded poly(lactic-co-glycolic acid) (PLGA) nanofibers were prepared through coaxial electrospinning. The effects of PLA anchors and drug/biomolecule-loaded PLGA nanofibrous membranes on improving the pullout strength of pedicle screws from artificial bones were investigated. The in vitro release characteristics of simvastatin and BMP-2 from the nanofibers were evaluated using high-performance liquid chromatography and enzyme-linked immunosorbent assay, while the in vivo elution of simvastatin was assessed in a rabbit model with histological examinations. The results demonstrate that electrospun drug/biomolecule-eluting nanofibers, when wrapped around pedicle screws, enhance the screws’ pullout strength. Additionally, the nanofiber/screw system provides a sustained release of simvastatin and BMP-2 for over 30 days in vitro and 4 weeks in vivo. Histological analysis also confirmed the biocompatibility of nanofibrous anchors. Hybrid resorbable anchors and drug/biomolecule-eluting nanofibers show potential for improving screw fixation and serving as a platform for extended drug delivery.