Bone cement and antibiotics.

Antibiotics of various kinds were added to the powdered polymer of methylmethacrylate in a concentration of 1 g antibiotic/40 g cement, prior to the addition of the liquid monomer. Specimens were subjected to mechanical testing by loading them in direct compression on a 20-ton Instron Universal Testing Machine, and load deflection curves were recorded. It was found that the addition of antibiotics does have an effect on the mechanical strength of the cement--the loss was small, less than 10% for both the compressive strength and the elastic modulus, provided the antibiotic was in powder form. Liquid antibiotics resulted in a greater loss of the compressive strength of the mixtures, but specimens tended to be less porous. In vitro studies of the antibiotic properties of the mixtures demonstrated potent antibacterial activity in all the antibiotics tested, except chloramphenicol. Possible clinical applications are discussed. Further in vivo studies are needed before widespread clinical use can be advocated.