OBJECTIVETo assess possible beneficial effect in prevention of osteomyelitis by anti-infective reconstituted bone xenograft (ARBX) in the rabbit.

METHODSA proximal tibia osteomyelitis rabbit model was used in which staphylococcus aureus was injected through a bony window, followed by immediate implantation of three ARBX pellets containing 30 mg of slowly-delivered gentamicin in group A, three pellets of RBX in conjunction with intramuscular gentamicin (30 mg) for 5 days in group B, three pellets of RBX without antibiotic in group C. Specimens were harvested 8 weeks postoperatively for gross observation, radiological, histological and bacteriological evaluation, comparing the three groups with regard to the beneficial effect of the above procedures in preventing osteomyelitis.

RESULTS(1) Bacteria counting, modified Norden scoring, and gross and microscopic evidence for osteomyelitis in group B were less than those in group C (P < 0.01). (2) In group A, bacteria culture and counting yielded 0 values at 8 weeks, while radiologically modified Norden scoring for osteomyelitis gave by far the smallest values among all three groups (P < 0.01) with no evidence of osteomyelitis found in gross and histological examinations.

CONCLUSIONS(1) Conventional systemic administration of antibiotics are reasonably effective in prevention of infection, but the anti-infective effect usually is not strong enough to prevent osteomyelitis when used along with primary bone grafting. (2) Apart from its osteoconductive and osteoinductive effects, ARBX is capable of slowly delivering antibiotics, thus being highly anti-infective when administered locally, so it could be used for primary grafting to repair a contaminated bone defect for effective prevention of osteomyelitis.