The Study Of Dog Femoral Condyle Defect Repair With Whisker-covered Porous Calcium Phosphate Bioactive Ceramic

Tricalcium calcium phosphate bioactive ceramic mainly includes tri-calcium phosphate(TCP),hydroxyapatite(HA),biphasic calcium phosphate(BCP),its great bone inductivity,bone conductivity,bioactive ablity was widely proved in many researches.After the material implanted into a bone defect model or muscle,as the time wents,new bone emerges with bloood vessels around under X-ray imaging,computerized tomography(CT),pathology sides observation.As a well developed bone graft substite,some commercial products of bioactive calcium phosphate ceramic already applied in clinical,especially in the areas of big sized bone repair,bone fusion,artificial eye,etc,the material had get many good treatment effects.However,the poor mechanical properties of the material had been a mortal drawback,which made the material hardly to be used alone in some load-bearing bone defects.Our research team recently developed a novel whisker-covered porous calcium phosphate scaffold through hydrothermal process,the mechanical properties improved greatly without add any other substances inside the material,however,the bioactive properties and bone repair ability still need to be tested if it was affected.Porous bioactive calcium phosphate scaffold was preparaed with sugar ball occupying method,porosity was 78%-80%,diameter of the big sized pore was around 500?m,after the scaffolds finished preparing,some of the scaffolds successfully whiskered with a hydrothermal method. 20 healthy adult beagle dogs were selected for the study,ages were around 1 year old,male and female unlimited,using self-control researh method.A 1cm deep,diameter 1cm,cylinder shaped bone defect was created at the lateral femoral condyle for each leg of all the animals,the left side implanted with a suitable sized BCP porous scaffold as control group,while the right leg implanted with a whisker-covered scaffold as experimental group.At thetime of 2 4,8,12 week after the surgery,X-ray,Dual Energy X-ray Absorptiometry(DEXA) test were conducted for 15 animals,Lane-sandhu X-ray bone healing evaluation were coducted based on the X-ray images.At the time of 6,12,18 week,5 animal were sacrificed respectedly for the pathologhy slides,general observation of the femoral condyle,the remained animinals keep breeding for long period observation.General condition of all the animinals after surgery were fine,most animals recovered to normal gait 2 weeks after the surgery,none case get bone marrow infection or pathology fracture.X-ray: With the increase of time, the interface between bone defect and normal bone of two groups gradually blurred, disappeared, and completely fused at 12 weeks. The material in the control group was partially dissolved, while there was no obvious dissolution in the experiment group. No significant difference in the X-ray score was found between two groups at different time points.Dual-energy X-ray: With the increase of time, the bone mineral density of the two groups both increased gradually, but there was no significant difference in the bone mineral density at different time points between these two groups. These results demonstrate that the porous calcium phosphate ceramics after the whiskering process has good ability to repair the defects of femoral condyle.Pathological biopsy: as time elapse,the pore wall and the bone defect surface of 2 groups were gradually replaced by bone tissue, finally,in the outer surface,a bone bridge totally covered the outer surface of the defect,at the time of 18 week,bone haversian system were visible at both of the groups; the material of the control group,gradually dissolved after implantion and finally disappeared; but the experimental group,as the growth of the time, although there are partly dissolved, but still have a few part not absorpted.All test data showed that the whisker-covered material after processing, didn't pose any influence for the bioactivity, and didn't induce any infection or cytotoxicity.Whisker-covered material,osteogenesis abilitydidnt get any decrease,which means good ability to repair big sized bone defect.As the material is becoming widely used in hospitals,microstructure modification of whiskering process provide a suitable choice for some load-bearing bone defect reapir.