A study was performed to investigate the effectiveness of
hydroxyapatite cement (HAC) as a new carrier system in the treatment of chronic, posttraumatic
osteomyelitis. In the in vitro study, release of
gentamicin from standard cylinders of HAC were measured by
agar diffusion test. As a representative for mechanical properties, compression strength was measured in order to detect changes when mixing HAC with
gentamicin. In the in vivo study, bone
infection was induced according to the model of Norden by injection of 1 ml Na-morrhuat and 3 x 10(6)CFU Staphylococcus aureus. After 3 weeks, when chronic stage of
infection was obtained, 17 animals were treated by
debridement and filling the marrow either with HAC alone or HAC mixed with
gentamicin (32 mg/g). Animals of the control groups were left untreated. After 6 weeks, all animals were sacrificed. Hematological, radiological, microbiological and histological examinations were carried out by covered investigation. Best evidence of the efficiency of treatment was observed in histopathological and microbiological findings. In all swabs of the control groups, taken 6 weeks following
infection S. aureus were detected which were clonal to the strain used for induction of
osteomyelitis. In HAC/
gentamicin-treated animals, no growth was detectable after 7 days of culturing in BHI bouillon. In the HAC/
gentamicin-treated group, there was no histopathological evidence of
infection. In all other groups different stages of chronic
osteomyelitis were found. No side effect was observed, neither locally nor systemically by HAC or
gentamicin. Therefore, HAC is considered to be a very effective carrier for
antibiotics in treatment of chronic, posttraumatic
osteomyelitis.