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Methicillin-resistant Staphylococcus aureus (MRSA) septic arthritis is frequently associated with a poor clinical outcome. Joint reconstruction may be worth attempting in patients with a history of persistent MRSA infection. Here we report an unusual case of MRSA septic arthritis of the knee joint that was treated successfully by joint replacement after initial placement of antibiotic-loaded hydroxyapatite (HA) blocks.

We report an unusual case of a giant femoral abscess caused by postoperative osteomyelitis after treating a fracture of the femoral shaft. The patient ignored it until the abscess began to interfere with knee flexion, but no symptoms of inflammation such as fever, pain or abnormal laboratory values were found. Within the marrow cavity, many plasma cells produced immunoglobulins G and M, and the level of these substances in the abscess fluid connected to the bony focus were higher than the serum levels. It was concluded that the inflammation in this case signified a peculiarity in a primarily chronic process.

The kinetics of drug release from fibrin adhesive agent (consisting of fibrinogen, factor 8, thrombin, aportinin and calcium chloride)-antibiotic compound and efficacy on rat experimental osteomyelitis were studied. To enhance the slow release activities of antibiotic, a mixture of fibrin clots was freeze-dried. Effects of freeze-drying were to make a fibrin clot an interlinked pore and to increase crosslinking rate containing an antibiotic. A diffusion test from aminoglycoside (Arbekacin Sulfate: 200 mg) compound was carried out. In vitro study freeze-dried antibiotic compound (FFAC: 1 cm3) was placed in saline (3 ml). The saline was replaced every 48 h and the previous solution was stored at -45 degrees C until assay. The result was that a concentration of 0.4 mg/l, sufficiently high to control Staphylococcus aureus strain IM2-42, was maintained within nine exchanges of saline after 18 days. In vivo animal experiments, FFAC (2 x 2 x 3 mm) were tested in rats with established Staphylococcus aureus osteomyelitis in the proximal tibia. The animals were observed for radiographic signs of infection and tissue was examined histopathologically. Bacterial counts by bone cultures were statistically lower in rats implanted with FFAC than in those only given a drug-free FFC and curettage. Radiographical and histological observations also showed beneficial effects of the FFAC. The results suggest that the FFAC provide a simple drug delivery system, and may be a promising alternative treatment for osteomyelitis.

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.