A simulated large joint model has been established to help better understand the elution mechanics of antimicrobial agents and the devices used to deliver them to a large human joint. This model is unique to previously published models in that it more accurately represents the environment of a large human joint. The model was employed to evaluate four brands of commercial medical-grade calcium sulfate. These products were evaluated in both an unaltered state and when mixed with antibiotics.

The use of calcium sulfate as an antibiotic delivery vehicle is a growing treatment option used by surgeons in the face of infection following joint replacement surgery. Calcium sulfate can be mixed with antibiotics and formed into small beads, which can be delivered during surgery to the local site of infection. We performed a mixing study to formalize mixing methods for individual and combined antibiotics with a synthetic calcium sulfate product. We report our mixing formulas and set times.

Bacterial biofilm infections of artificial knees are treated by mixing antibiotics into bone cement and calcium sulfate beads. We designed a knee size model to show that cement alone killed biofilms on orthopedic materials and prevented their spread close to the cement, but adding beads significantly killed biofilms further away. The model is useful in helping show how both the spread and the amount of antibiotic carrier can kill biofilms that might be in different places in the joint.