Injectable Nanofiber Gel Enhances Osseointegration in a Rabbit Model

Abstract

High insertion torque can cause conventional bioactive implant coatings to delaminate, generating debris and compromising osseointegration. We developed and evaluated an injectable, self-assembling peptide nanofiber interface designed to be applied in the osteotomy site to enhance biomechanical stability and accelerate bone formation. A multifunctional, injectable gel was formed from self-assembling peptide amphiphiles designed to be osteoinductive, adhesive, and antimicrobial. In a rabbit model, custom titanium implants were placed with either the nanofiber interface or a standard sand-blasted, large-grit, acid-etched (SLA) surface. Osseointegration was evaluated at 3 and 5 wk using micro–computed tomography (micro-CT) for bone-to-implant contact (BIC) and bone volume/total volume (BV/TV), as well as biomechanical reverse torque testing. At 5 wk, implants with the nanofiber interface demonstrated significantly superior osseointegration. BIC reached 58.7% compared to 50.5% for SLA-treated implants (P < 0.001). BV/TV was also significantly higher at 51.8% versus 42.6% for the SLA group (P < 0.001). Crucially, biomechanical stability was markedly improved, with the nanofiber group withstanding a reverse torque of 53.2 N·cm, significantly higher than the 41.8 N·cm for the SLA group (P < 0.01). This injectable nanofiber interface successfully overcomes the limitations of traditional coatings by enhancing bone–implant integration and providing superior biomechanical stability. Uniquely, it is designed to prevent or repair drilling-induced microdamage, occupy peri-implant microcracks with a structural nanoscaffold, and act as a flowable, conformal osteotomy liner when applied prior to implant insertion. This practical approach represents a promising strategy to improve long-term clinical outcomes, particularly in patients with compromised bone quality or a higher risk of implant failure.