Antibacterial and Bone Ingrowth Properties of Iodine Ion‐Releasing Titanium Implant With Gradient Pores: An in Vivo Study

ABSTRACT

Titanium implants are widely used in orthopedics and spinal surgery, but implant‐associated infections remain a major clinical challenge that often necessitates implant removal. To address this issue, we evaluated whether an iodine‐loaded porous titanium implant with a gradient pore design could balance antibacterial activity and bone formation. The structure transitions from large outer pores to smaller inner pores, enhancing osseointegration while providing a greater surface area for iodine ion loading. Implants were fabricated by selective laser melting and surface‐modified to incorporate iodine ions. In vivo experiments using rabbit femoral condyles demonstrated that gradient implants (Ti‐D) showed bone ingrowth comparable to larger pore implants at 4 weeks. Iodine‐treated implants (ITi‐D) exhibited sustained ion release, strong antibacterial activity against Staphylococcus aureus and Escherichia coli , and no clear cytotoxicity in vitro. In vivo subcutaneous infection models confirmed significant antibacterial efficacy of ITi‐D, while blood tests showed no systemic toxicity up to 90 days. Compared with uniformly porous implants, ITi‐D achieved an optimal balance between antimicrobial performance and biocompatibility. This dual‐functional approach addresses the longstanding tradeoff between infection control and osseointegration in porous titanium implants.