ANTIBIOTIC-LEACHING FROM POLYMETHYLMETHACRYLATE BEADS

Aminoglycoside-impregnated polymethylmethacrylate beads, which are use d to deliver antibiotic directly to infected sites in the musculoskele tal system, are available as a manufactured product or they can be mol d-made by a pharmacy or hand-rolled by the orthopaedist in the operati ng suite. We investigated the leaching of antibiotic from each of thes e types of beads. Our hypothesis was that the elutions of antibiotic f rom the three types of beads are similar. Three study groups (hand-mad e, mold-made, and manufactured beads), each composed of four five-bead subsets, were formed so that twenty beads of each type were tested. E ach bead was leached daily in a two-milliliter aliquot of normal salin e solution throughout a sixty-day period, and the aminoglycoside conce ntration in twenty of these aliquots was determined. Analysis of varia nce showed no statistically significant differences when the antibioti c elutions within each subset, between the different subsets, and betw een the three groups were compared. The clinically important finding o f this investigation is that the leaching characteristics of the three types of aminoglycoside-impregnated beads are equivalent when the bea ds have been fabricated out of com arable materials.