Hydroxyapatite and cobalt ferrite composites as ciprofloxacin release systems for the treatment of osteomyelitis - An experimental study.

Osteomyelitis is a severe bone infection that requires prolonged and aggressive treatment. Local drug delivery systems have been investigated to improve recovery and reduce the need for extended systemic antibiotic therapy. This study evaluated composites of synthetic hydroxyapatite associated with cobalt ferrite (CoFe₂O₄) magnetic nanoparticles as a ciprofloxacin delivery system for infected bone defects. New Zealand rabbits were used as an experimental model, with osteomyelitis induced by inoculation of Staphylococcus aureus into a humeral bone defect. Fifteen days after inoculation, the animals were allocated into five groups and underwent surgical debridement followed by implantation of biomaterials in the treated groups, while control groups received no biomaterial. Bone marrow samples were collected for bacterial culture before implantation. Clinical and radiographic evaluations were performed at 0, 15, and 42 days, and samples collected at 42 days were analyzed by micro-computed tomography and histology. Radiographic evaluation demonstrated a significant increase in bone density 15 days after bacterial inoculation. Micro-computed tomography revealed extensive cortical bone destruction and high cortical porosity in all groups, with no significant differences between treated and control groups. However, histological analysis showed significantly greater new bone deposition in treated groups, while necrosis was more frequent in controls. These findings indicate that the tested biomaterials positively influenced bone regeneration.