Objective To study the effect of porous coating of titanium alloy prosthesis with different pore size and porosity on osseointegration.Methods Three kinds of titanium alloy prosthesis with different porous surface were manufactured by 3D printing technology.The micropore diameter and the porosity was (260.5±34.5) μm and 68.1% in type a, (553.2±16.7) μm and 79.2% in type b, and (749.8±15.0) μm and 89.0% in type c.Twenty-seven New Zealand white rabbits were randomly divided into three groups, which were group A, group B and group C, and three kinds of prostheses were implanted into the femoral medullary cavity of rabbits.Three rabbits of each group were randomly sacrificed at the end of the fourth, eighth, twelfth weeks after operation.Micro-CT were taken to observe the condition of bone formation of each group, while bone volume fraction (BV/TV) and tissue mineral density (TMD) were measured by Micro-CT, the peak pull-out load of each group was measured by pull-out testing.Results At the fourth week after operation, all of the prostheses were in good position, the area within and around pores showed low signal, and no obvious bone formation was found.Distal parts of prostheses were only covered by little immature osteoid, but most of it was fibrous connective tissue and oboslete blood clot which could be washed away easily.The BV/TV, TMD and peak of pull-out load showed no statistical difference between any two groups (all P>0.05).At the eighth week after operation, the area within and around pores showed medium signal, which was immaturate osteoid, and especially in the group A, which was more than the other two groups.Distal pull-out specimens were all covered by bone in the three groups, and the middle of prostheses of group A also showed bone deposition.The BV/TV and TMD showed no statistical difference between any two groups, but the peak pull-out load of group A was higher than that of group B and group C (all P<0.05).At the twelfth week after operation, the area within and around pores all appeared high density shadow, which was bone deposition, and formed locking junction in three dimension, group A was more than group B and group C, no obvious osteolysis was found.All the parts of prostheses of group A were evenly covered by a lot of bone, the distal and proximal prostheses of group B and group C appeared significant bone formation, but less than that of group A.The BV/TV and TMD of group A was significant higher than that of group B and group C (P<0.05), the peak pull-out load showed statistical difference between every two groups (all P<0.05), and the sequence from high to low was: group A, group B, and group C.Conclusion The porous coating of titanium alloy prosthesis with pore size of 226-295 μm and porosity of 68.1% is the best for enhancing osseointegration, which shows good biomechanical property.%目的 探讨钛合金假体表面涂层微孔孔径和孔隙率对骨整合的影响.方法 采用3D打印技术打印3种不同微孔孔径和孔隙率的钛合金假体,第一种假体表面微孔孔径(260.5±34.5)μm、孔隙率68.1%,第二种孔径(553.2±16.7)μm、孔隙率79.2%,第三种孔径(749.8±15.0)μm、孔隙率89.0%,分别标记为a、b、c型假体.选择新西兰大白兔27只,随机分为A、B、C组各9只,分别将a、b、c型假体植入兔股骨髓腔.术后4、8、12周,每组随机处死3只,通过Micro CT扫描观察各组成骨情况并测量骨体积分数(BV/TV)、组织矿物密度(TMD),通过拔出试验检测各组最大拔出力.结果 术后4周,各组内植物均在位,微孔内及周围呈低信号,无明显沉积骨质;拔出标本仅远端有少量未成熟骨质,表面多覆盖纤维结缔组织及陈旧血凝块,处理标本时可轻易洗去;三组BV/TV、TMD及最大拔出力比较差异均无统计学意义(P均>0.05).术后8周,各组微孔内及周围均见部分中密度影,为未成熟骨质,A组相对较多;三组拔出标本远端均有明显骨质覆盖,A组假体体部表面可见沉积骨质;三组间BV/TV、TMD比较差异均无统计学意义(P均>0.05),但A组最大拔出力明显高于B、C组(P均<0.05).术后12周,各组微孔内及周围均见高密度影,为沉积骨质,且伸入微孔内部,形成锁结,A组多于B、C组,无明显骨溶解;A组整个假体表面均匀覆盖较多骨质,B、C组远端和近端可见明显沉积骨质,但少于A组;A组BV/TV、TMD明显高于B、C组(P均<0.05);最大拔出力A组>B组>C组,组间两两比较P均<0.05.结论 钛合金假体表面涂层微孔孔径226~295 μm、孔隙率68.1%有利于促进骨整合,并具有较好的生物力学性能.
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