Self-foaming PMMA bone cement for osteomyelitis: Enhanced antibiotic delivery with translational potential

The treatment of osteomyelitis remains a challenge in orthopedics. The burst antibiotic release and low total elution of conventional antibiotic loaded PMMA bone cement limited its therapeutic efficacy in clinical application. Herein, a self-foaming PMMA cement was developed with citric acid and sodium hydrogen carbonate as foaming agents (FA) to create an interconnected microporous structure which facilitated antibiotic release. The PMMA + 10 %FA formulation satisfied the ISO 5833-2002 compressive strength requirement (>70 MPa) and sustained an effective bactericidal concentration of Van (>15 mg/L) for over 28 days, yielding a 4.6-fold higher cumulative drug release when compared with the conventional PMMA. Micro-CT and mercury intrusion porosimetry demonstrated that FA incorporation elevated open porosity and refined the pore-size distribution which enabled sustained drug diffusion. The cytocompatibility was verified using MC3T3-E1 cells and HUVECs. In addition, PMMA + FA demonstrated potent in vitro anti-MRSA activity, and effective in-vivo infection control and osteogenic capacity in a rat femoral osteomyelitis model. This self-foaming cement, prepared with FDA-approved agents and a simple protocol, offers a clinically adaptable strategy for enhancing local antibiotic delivery and pro-osteogenic activity.