Effect of gentamicin on shear and interface strengths of bone cement.

Antibiotic impregnated cement offers a potential method for salvage of infected total joint replacements. The addition of gentamicin in concentrations of .5, 1.0, and 2.0 per 40 significantly affects the shear strength of Palacos acrylic bone cement. The clinical significance of this strnegth drop is not clear. Large grained antibiotic additives have deleterious effect on shear strength. Measurements were made to determine the effect of gentamicin concentration on the bone-cement interface strength but no trend could be determined. The interface strength was much less than the strength of Palacos alone and suggested that bone strength is the limiting factor.