Rabbit Peri-joint Infection (PJI) Model

• Duration of study – 24 hours to 4 weeks

• Lead time – 30 days

• Standard results – Gross Observations, Histology, Microbiology

MODEL UTILITY:

The rabbit peri-joint infection model is used to screen coated implants, surgical washes, antimicrobial or anti-biofilm treatments for the ability to reduce or eliminate microbial contamination in a joint defect or implant.

HOW THE MODEL WORKS:

IIn this model, a stainless-steel screw with ultra-high-molecular-weight polyethylene (UHMWPE) washer is implanted transversely into the lateral femoral condyle.  These implants are placed in the non-weight bearing, non-articulating aspect of the lateral femoral condyle.  The implant and joint space are then infected with a microbial inoculum.  This inoculum is typically Staph aureus, but could also be MRSA, Pseudomonas, E. coli, etc. The test material may be delivered before incision closure (e.g. for surgical washes) or days after closure (antimicrobials or biofilm disruptors), as just two examples. 

At the end of the protocol, the animal is euthanized and gross observations of the joint and implant are made.  The implant, tissue from the area proximal to the implant, and/or synovial fluid are then removed and processed to determine the bioburden present. Samples of tissue and bone are also taken for histological analysis.

EXAMPLE DATA:

Advantages:

This model is highly representative of a human joint infection while also being a bit less costly than a large-animal model such as a goat, sheep or dog.

The model permits the use of a wide range of microorganisms. Although not yet tested, it is likely that a microbial cocktail containing more than one bacterium would work as well.

Disadvantages:

This model is surgically intensive and therefore does not lend itself to high-throughput screening. Our veterinary surgeon can typically perform surgeries on 4-8 rabbits per operating room per day. (For screening actives, we recommend our rat subcutaneous model).