3D-printed antibiotic-eluting pedicle screws for antimicrobial prophylaxis in instrumented spinal fusion

<h2>Summary</h2> Antibiotic bone cement is the only approved material for antibiotic prophylaxis in instrumented spine surgeries. However, its application has been linked to multiple complications and risks for patients and surgical staff. Here we report the fabrication of customizable cannulated and fenestrated Ti-6Al-4V pedicle screws, designed to provide sustained antibiotic elution through an injectable hydrogel comprised of sodium polyacrylate (SP), doxycycline, and β-tricalcium phosphate. The 3D-printed screws and SP hydrogels are compatible with human fetal osteoblasts, enhancing attachment, proliferation, and mineral deposition on the micro-structured implant surface, which all serve as key indicators of new bone formation. Sustained antibiotic elution through the screws' fenestrations proved effective at inhibiting <i>Staphylococcus aureus</i> growth <i>in vitro</i> and <i>ex vivo</i> using a bacterially infected porcine lumbar spine model. The injectable hydrogel and 3D-printed antibiotic-eluting screws offer potential as a patient-specific and safer alternative to traditional cemented machined implants for antimicrobial prophylaxis in instrumented spinal procedures.