| Objective:In this study,the effects of different porosity of porous titanium implants on bone ingrowth were evaluated by observing the bone ingrowth of 3D printed porous titanium implants with different porosity in rabbit experiments.Methods:The porous titanium plates with different porosity were prepared by 3D printing.the porosity was designed as follows: A group(35%),B group(55%),C group(75%).18 healthy New Zealand rabbits,male or female,were randomly divided into the above three experimental groups A,B and C.After general anesthesia,routine disinfection of towels.The lateral femoral incision of the left hindlimb was taken and the femoral shaft was exposed layer by layer.The 1 cm × 2 cm area in the middle of femoral shaft was selected as the plate area.The periosteum was removed,the bone cortex was polished with a grinding drill until fresh bleeding appeared on the bone surface,and punch micropores with 1.0 mm Kirschner wire,the spacing of each micropore was about 2~3mm.the titanium plate was placed properly and fixed with locking screw.Three rabbits were sacrificed in each group at the 4th and 16 th weeks after operation.Each femoral shaft specimen was taken for X-ray examination and general observation to observe its fixation and surrounding osteogenesis.At the last time of the experiment(16 weeks after operation),each specimen was sliced into non-decalcified bone tissue for V-G staining.The whole image including prosthesis was collected by computer image acquisition system.The area of new bone tissue and the rate of new bone formation in porous titanium implants were judged and calculated by Image-Pro Plus 6.0 image analysis system(New bone formation rate = area of new bone tissue / total area of pores in the prosthesis × 100%).Results:Gross observation: 4 weeks after operation,fibrous tissue and a small amount of original callus were observed around and between the titanium plate and bone surface in each group.At 16 weeks after operation,new bone tissue was formed between titanium plate and bone surface,and callus was formed around titanium plate,and individual titanium plate was wrapped by callus.X-ray observation showed that 4 weeks after the operation,vague shadows could be seen between titanium plates and bone surfaces in each group,and some titanium plates and bone surfaces had gaps.At 16 weeks after surgery,callus was observed between the titanium plate and the bone surface,and most of the titanium plates were closely adhered to the bone surface.Histological observation: in group A,new bone formation was observed around the titanium plate,but only A small amount of bone tissue grew in the middle pore structure.In group B,the osteoclasts in the pore structure grew in,but there was a gap between them and the titanium plate.The density of new bone growth in the pores of group C titanium plates was high,and it was closely combined with the titanium plates.16 weeks after surgery,the rate of new bone formation in group C was significantly higher than that in group B and group A,and the difference was statistically significant(P < 0.001).Conclusions: 1.The pore structure of 3D printed porous titanium plate can allow new bone togrow in.2.Different porosity affects the effect of new bone ingrowth of 3D printed titaniumimplants.3.Among the three porosity of 35%,55% and 75%,75% porosity was morebeneficial to bone ingrowth than the other two groups.4.75% porosity 3D printed porous titanium plates can achieve good bone fusionwith properly treated cortical bone surface. |
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