Antimicrobial Biomaterials for Cranioplasty: A Systematic Review

Background

Cranioplasty is a surgical procedure performed to reconstruct the calvarium, yet it carries a significant risk of infection and subsequent graft failure. Surgical asepsis, systemic antibiotic prophylaxis, and topical antiseptics may reduce this risk, but recent attention has focused on incorporating antimicrobial agents or properties directly onto or into the implant. This systematic review assesses the efficacy of antibacterial-modified cranioplasty grafts in reducing infection risk.

Methods

Following a registered protocol, 2 reviewers independently searched and screened for studies describing antibacterial-modified cranioplasty grafts. Inclusion criteria included in vitro, in vivo, and clinical studies evaluating altered cranioplasty implants (e.g., antibiotics or nanoparticles embedded, coated, or added to a reservoir). The primary outcome measures were suitable measures of infection, with additional outcomes including antibiotic release profile.

Results

Twenty studies met the inclusion criteria: 10 in vitro studies (2 also reporting results of in vivo models) and 10 clinical studies (n = 234 patients). Polymeric, ceramic, or hydrogel grafts were impregnated or coated with various antimicrobial agents, most commonly aminoglycosides. In vitro studies consistently demonstrated high local antibiotic concentrations and reduced bacterial colonization, with a biphasic release profile characterized by an early burst and sustained low-level elution. In limited in vivo studies, systemic drug levels remained low. Clinical studies reported a combined complication rate of 2.99%. While this may indicate an improvement over historical complication rates, most studies lacked appropriate comparators and sufficient power: only 1 study attempted a statistical comparison with historical data, finding a nonsignificant reduction in infection (2.6% vs. 7.8%; P = 0.179).

Conclusions

Antimicrobial modifications to cranioplasty materials show promising preclinical results, with favorable local release profiles and minimal systemic distribution. Early clinical experiences suggest a possible reduction in infection rates, but the current evidence is limited by small sample sizes and methodological biases. Well-designed comparative trials with standardized reporting are necessary to establish definitive clinical efficacy and to guide optimal material-antibiotic combinations and delivery methods.