Antibiotic-loaded hydroxyapatite blocks in the treatment of experimental osteomyelitis in rats

Department of Orthopaedic Surgery, Gifu University School of Medicine, 40-Tukasamachi, Gifu 500, Japan *Institute of Anaerobic Bacteriology, Gifu University School of Medicine, 40-Tukasamachi, Gifu 500, Japan Corresponding author: Dr M. Itokazu. Received November 19, 1996 Revision received February 10, 1997. Accepted February 10, 1997 A novel drug delivery system for osteomyelitis was developed in which a porous hydroxyapatite block (HAB) is loaded with antibiotic by a centrifugation method. In this study, implantation of HABs loaded with the aminoglycoside antibiotic, arbekacin, were tested in established Staphylococcus aureus osteomyelitis in the proximal tibia of rats after debridement of the marrow cavity. The animals were observed for radiographic signs of infection and tissue was examined histologically. The infections were also evaluated by bone cultures. Bacterial counts were statistically lower in rats implanted with an antibiotic-loaded HAB than in those given a drug-free HAB. Radiographical and histological observations also showed beneficial effects of the antibiotic-loaded implant. The results suggest that the centrifugation method for loading HABs provides a simple drug delivery system. These antibiotic-loaded HABs may be useful for filling grafts in osteomyelitis.