Local plate infections in a rabbit model

We used 30 New Zealand white rabbits to compare the susceptibility to bacte rial challenge of two different orthopaedic implants: a standard-design sta inless steel plate, or a PC-FIX titanium plate applied on the right tibia w ere compared with sham operated animals. Directly after surgery Staphylococ cus aureus (10(8)-10(9) colony forming units) were inoculated close to the plate. The infection rate in the group of plated animals was 11/20 (stainle ss steel plates 6/10, PC-FIX titanium plates 5/10) and in sham operated ani mals only 1/10. Thus, a foreign body increased the risk for infection (p = 0.02). However, the implant type did not appear to be of major importance w hen the bacteria were inoculated locally. In experimental haematogenous inf ections, by contrast, implant design and material are considered to be impo rtant. This may either indicate different pathogenic mechanisms in locally and haematogenously induced infections, or simply that the large number of microorganisms in local inoculation 'overload' the normal defence systems. (C) 1999 Elsevier Science Ltd. Al! rights reserved.