Orthopaedic Implant Infection


There were several issues which were particularly highlighted, including the prospects for fabricating patient-specific, open-cellular implants or orthopaedic appliances with closely matched stiffness to avoid any significant bone stress shielding, as well as the inducement of bone cell ingrowth to create a more stable appliance without cement. The issue of infection was also briefly addressed with the proposal that such open cellular structures might accommodate nano silver particles to serve as a long-term antibiotic within the implant; similar to the incorporation of antibiotics within implant cement compositions.

The major problem in orthopedic implant infection is the growth of massive mattes or biofilms of infectious bacteria which can form over the metal surface, especially roughened surface areas. The immune system cannot counter these massive infection systems, and the only recourse in most instances is the removal of the appliance and its sterilization along with the healing of the wound area intense antibiotic regimes. Most infections are hospital acquired and of the various infections which strike roughly 2 million people annually in the U.S., 0.05% cause death. Orthopaedic implant infection rates range from 0.3% to 8.3% and occur by entry of pathogens into the wound during surgery, the spread of infection from a local source, hematogenous (blood transport) spread, or the recurrence of sepsis in a previously infected joint.

With roughly 400,000 primary hip arthroplasties and nearly 1 million total knee anthroplasties in the U.S. in 2012, the market exceeds $20 B. While this market represents mostly smooth and highly polished implant components, prospects for 3D-printed or electron beam and laser beam melt-fabricated, patient-specific open-cellular appliances will require careful evaluation of the infection issue, especially in light of the continued mutation of pathogens against the most effective antibiotics.

The practioner might consider discontinuing the practice of routinely prescribing prophylactic antibiotics for the patients with hip and knee prosthetic joint implants undergoing dental procedures…. patient preference should have a substantial influencing role. In the absence of reliable evidence linking poor oral health to prosthetic joint infection, it is the opinion of the work group that patients with prosthetic joint implants or other orthopaedic implants maintain appropriate hygiene. These recommendations were based on the fact that no clear association between the organisms found in implant infections and those involved in bacteremia exist.

Aaron Province
Journal of Biotechnology & Biomaterials
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