Infection adjacent to titanium and bone cement implants: an experimental study in rabbits

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Infectious disease research

Background:

• Surgical site infections are a significant complication following orthopedic implant procedures.
• Understanding the host-implant-pathogen interaction is crucial for preventing and managing infections.
• Titanium and bone cement are common biomaterials used in orthopedic implants.

Purpose of the Study:

• To evaluate the susceptibility of bone surrounding titanium and bone cement implants to Staphylococcus aureus infection in a rabbit model.
• To assess the radiographic, bacteriological, and histological signs of infection after bacterial inoculation.
• To determine the resistance of the bone-implant interface to bacterial colonization.

Main Methods:

• Pure titanium cylinders and bone cement pieces were implanted into rabbit tibial metaphyses.
• Staphylococcus aureus (10^4, 10^6, 10^8 CFU) was injected into the implant central holes.
• Radiography, bacteriological cultures, and histological biopsies were performed four weeks post-injection.

Main Results:

• Radiographic signs of infection were observed in 11/22 legs inoculated with 10^6 or 10^8 S. aureus.
• No radiolucent zones, indicative of loosening, were observed around implants.
• Bacteriological cultures were negative for all titanium implants, but positive in 4/22 cement implants.
• Histological examination revealed potential healing of bone infection in some cases.

Conclusions:

• Unloaded titanium and bone cement implants demonstrate considerable resistance to Staphylococcus aureus infection in the bone surrounding the implant.
• The host bone tissue exhibits a degree of resistance to infection, and spontaneous healing may occur.
• Further research is warranted to elucidate the mechanisms of resistance and healing in the bone-implant interface.