Study on the effect of different porosity of 3D printing porous titanium implants on bone ingrowth

ObjectiveTo investigate the effects of different porosity of 3D printing porous titanium implants on bone ingrowth through animal experiments.

MethodsEighteen healthy New Zealand rabbits were randomly divided into A, B and C groups.Three kinds of porosity porous titanium plates in A, B and C groups prepared by 3D printing technology were 35%, 55% and 75%, respectively.The titanium plate was implanted into the femoral shaft plate area of rabbits.After 4 weeks and 16 weeks of operation, the femoral shaft specimens were examined using X-ray, and the gross and histological observation in bone tissue section were implemented.The rates of new bone formation in three groups were compared.

ResultsAfter 4 weeks of operation, the fibrous tissue was found around the titanium plate and between titanium plate and bone surface, and no obvious callus formation was observed in each group.The results of X-ray films showed that some gaps were identified between titanium plate and the bone surface.After 16 weeks of operation, there were new bone connections around titanium plate and between titanium plate and bone surface in each group, a few titanium plates were wrapped by bone scabs, and the results of X-ray films showed that the titanium plate was closely attached to the bone surface.The results of histological observation showed that some new bone formation could be seen at the edge of titanium plate, but only a small amount of bone tissue grew into the middle pore in group A; In group B, some bone tissue grew into the pores, but there was a certain gap between pores and titanium plate; In group C, the density of new bone between pores of titanium plate was higher, and it was closely bound to titanium plate.The differences of the rates of new bone formation among three groups were statistically significant(P < 0.01), the rate of new bone formation in group A was significantly lower that in B and C groups(P < 0.01), and the rate of new bone formation in group B was significantly lower that in group C(P < 0.01).

ConclusionsThe pore structure of 3D printing porous titanium plate can allow new bone to grow in.Different porosities affect the effect of new bone ingrowth of 3D printed titanium implants The 75% porosity is more beneficial to bone ingrowth compared with 35% and 55% porosity.The printing porous titanium plates can achieve good bone fusion with proper treating cortical bone surface.