Palacos bone cement with and without contained gentamicin was tested for
antibacterial efficacy using a rabbit model of a knee hemiarthroplasty and
a challenge with intra-articular Escherichia coli. The
gentamicin-containing cement prevented infection from challenge with
Escherichia coli and protected against inadvertent operative infection as
well. Antibiotic concentrations in synovial fluid and urine remained in the
therapeutic range for three days, whereas levels in serum were always quite
low. Eight per cent of the gentamicin had leached out of the bone cement by
eight days, most of it during the first day. Thereafter, extremely small
amounts of gentamicin left the cement on a daily basis. The amount of
antibiotic leaching out in vitro was proportional to the surface area of
the cement. More eluted into serum than into saline.