Experimental Study Of GM/BG In The Treatment Of Rabbit Tibial Chronic Osteomyelitis

ObjectiveThrough the establishment of tibial osteomyelitis model,after debridement, implant the gentamicin / bioactive glass (GM / BG), to observe the ability to repair rabbit tibia Infected bone defects. provide a experimental basis for the treatment of chronic osteomyelitis .MethodsSelected 8 New Zealand white rabbits,weighing 2.25 ~ 2.75kg,female or male. Accord ing to ShenLin's method,took the right tibial as osteomyelitis model. 2 weeks postoperative, took radiological examination, and killed experimental rabbits then took the necrotic tissue from the cavitas medullaris to culture for bacterium , confirmed a clear expression of chronic osteomyelitis at the rabbit proximal tibia . Divided other 40 New Zealand rabbits into groups A, B, C, D average and randomly , after the successful modeling, the right tibia underwent debridement surgery, after operations GM / BG were implanted in group A at bone defects , BG were implanted in group B in conjunction with intramuscular gentamycin for 4 days, BG were implanted in group C at bone defects , in group D, without any materials. Recorded the gross situations after operations. Obtained blood and muscle tissue surrounding bone at the 1, 3,5,9,14,20, 27 days after operations in groups AandB, measured plasma concentrations and drug concentrations which from the muscle tissue by high performance liquid chromatography in the two groups .Took radiological examination at 0,4,8 weeks after operations for experimental animals to observe the healings of the osteomyelitis cases, To give a mark by norden'score at 4, 8 weeks, compared healings in each group, and killed all animals, observed the gross healings of the osteomyelitis cases by naked eyes,and took histological analysis for the tissues, analysis the healing in each group, took bacteriological evaluation, measured and calculated the average number of S. aureus per gram of sample in each groups. And analyzed data statistically in each group, then concluded. Results1 Gross situationThe wound in group A of 10 rabbits healed completely at 2 weeks postoperatively. Group B of 3 rabbits the wound healed completely , the wound of other 7 rabbits had sinus tract. 2 rabbits died in Group C, the rest 8 wound had secretions. 1 rabbit died in Group D and 2 rabbits delayed wound healing, another 7 had secretions.Specimens were harvested 8 weeks postoperatively, there were 10,10,8, 9 specimens in groups A, B, C, D, in group A, 10 specimens had normal shape, bone defect repaired completely. in group B, 3 specimens had relatively normal shape with mild hyperosteogeny on local bone,while other 7 specimens were deformed shape, bone defects were not repaired, BG were exposed, there was a little liquor puris in the defect regions. In group C, 8 specimens were were not repaired , BG exposed and surrounded by a little liquor puris. 9 specimens were not repaired in group D,destruction of bones were serious, medullary cavity were filled with inflam fibrous tissue and liquor puris .2 Measurement of plasma drug concentration and tissue drug concentration.In group A ,there was a high tissue drug concentrations of gentamicin, maintained for 20 days at least, while whose plasma drug concentrations were low and safety for system.In group B, the plasma drug concentrations were high as drug systematically used, but fell rapidly after drug withdrawal, plasma drug concentrations were below the MIC on the 5th day,and local tissue drug concentrations were very low.3 Radiological examination4 weeks postoperative, in group A, density of BG became weak, have not obvious periosteal reaction and bony destruction. in group B, 3 cases with the appearance of mild hyperosteogeny,and the remaining 7 cases and 8 cases in group C with the performance that density of BG became weak, integrated poorly with surrounding bones. in group D showed obviously periosteal reaction, hyperosteogeny and bone destruction. Compared group A with groups B, C, D the differences were significant on statistic. 8 weeks postoperative, in group A, BG had been absorbed largely, integrated well with surrounding bones, and the newly formed bones were well. In group B, appearance of 3 cases as group A, the rest appearance of 7 cases and and 8 cases in group C were obvious bone destruction, BG is integrated poorly with surrounding bones . In group D, sequestrum formed in defective areas and hyperosteogeny and bone destruction around the cortical bone. Compared group A with groups B, C, D the differences were significant on statistic.4 Histological examination 8 weeks postoperative ,In group A, 10 specimens of cortical bone defect were repaired well, structure of trabecular bone were rule, and normal marrow cavity was formed, but there was still a little BG unabsorbed. In group B ,3 specimens whose cortical bone were repaired, but most of the bodies were poor, BG were not absorbed completely, pore had little inflammatory cells. The rest of the 7 specimens whose cortical bone repaired poor, hyperosteogeny obvious, most BG were not absorbed , pore had a number of smaller abscesses. In group C all specimens of bone cortex were repaired bad, bone hyperplasia and destroyed, most BG were exposed and did not be absorbed. In group D, bone defects were not repaired,which were filled with a large number of inflammatory fibrous tissue and liquor pusis, hyperosteogeny and bone destruction serious and there were not new bone marrow trabeculation formed.5 Bacteriology examinationBacteria identified was Staphylococcus aureus bacteria,The number of Four groups of bacteria in culture-positive bone respectively were 1,8,8 and 9. In group A the number is (2.43±3.07)×10~2, group B(7.05±4.86)×10~4, group C (4.77±2.55)×10~7, group D(9.58±5.08)×10~6. C ompared group A with groups B, C, D the differences were significant on statistic.Conclusions1 After the debridement of chronic osteomyelitis, implanted GM / BG on the first time in the treatment of infected bone defects was effectively.2 After the debridement of chronic osteomyelitis , implanted GM / BG in the treatment of chronic osteomyelitis, the effect was better than implanted BG in conjunction with intramuscular ,and better than implanted BG alone .