A study on gentamicin impregnated biomaterials for treating induced-osteomyelitis in the New Zealand white rabbit animal model

Abstract

The treatment of osteomyelitis is still a major challenge in orthopaedics. A study of osteomyelitis and infection requires the use of a suitable animal model. The New Zealand White Rabbit (NZWR) is an acceptable experimental model that can be used for local delivery of antibiotics in osteomyelitis treatment as it can mimic the disease process in humans. The objectives of this study were to create osteomyelitis in the rabbit femurs and to analyse the treatment given via gentamicin impregnated with biomaterials beads. Thirty-six (36) NZWRs were used in the study. They were divided into two groups [Hydroxyapatite (HA) and calcium sulphate (CaSO4)] with four subgroups 3-, 6-, 12-, and 26-weeks intervals. There were two surgeries performed for each NZWR. The first was to induce the osteomyelitis by inoculating Staphylococcus aureus in the distal of the animal, and the second surgery was for debridement and biomaterial impregnated antibiotics implantation. The responses of the treatments (gentamicin impregnated with HA and CaSO4) to were evaluated through gross appearance, radiograph, micro-CT, microbiological, and histological examination. The rabbits were sacrificed accordingly to evaluate the healing process of the affected bone. The results showed osteomyelitis changes in all rabbits after the inoculation of the bacteria at 3 weeks. The rabbits’ weights reduced after three weeks of bacteria inoculation following the treatment with biomaterial impregnated antibiotics, they showed significant increase in weights at 12 and 26 weeks in both groups. The microbiology analysis at 26 weeks showed that no bacteria were isolated. All the defects at the drilled site of the distal femurs of the NZWRs were united at 12 weeks interval. The histological examination revealed healing of the infected area with the appearance of a new bone formation at 6 to 26 weeks. The micro-CT results revealed increased the trabeculae numbers with the treatments. The biomaterials containing CaSO4 disappeared by 26 weeks. There was completed bone healing at 26 weeks of interval for both groups. The results of the gentamicin impregnated with HA and CaSO4 for all parameters are comparable. Hence, the antibiotics impregnated with biomaterials are proven effective in the treatments of osteomyelitis. In conclusion, the results of this study show that gentamicin impregnated with biomaterial has a great potential to be utilised for the treatment of osteomyelitis.