Abstract:
Objective To analyze coating properties of porous artificial joints, including coating morphology and coating mechanical properties, and summarize the range of coating properties of current mainstream products, to provide references for the design and development of new products, as well as provide the basis for the long-term implant removal analysis. Methods Samples for the surface morphology, shear strength, and tensile strength of the coatings used in the experiment were prepared in accordance with ASTM F1854, ASTM F1044, and ASTM F1147 standards, respectively. The coatings were processed using plasma spraying. The surface morphology (coating thickness, porosity, and pore intercept) of the coatings for all 17 products (Nos. 1－17) was tested; for products Nos. 1－7 and Nos. 15－16, the shear strength test between the coating and substrate was conducted first in accordance with the test method of ASTM F1044. Then, according to the test method of ASTM F1147, the tensile strength test between the coating and substrate was conducted. For product No.17, the shear and tensile strengths of the composite coating and simple titanium coating were tested, respectively, according to the test method of ASTM F1044 and ASTM F1147. Results A total of 15 products (88.2%) had coating thicknesses between 300 μm and 500 μm. There were 16 metal-coated products (Nos. 1－16), of which 11 (68.75% of the total) had coating porosities between 30% and 50%, and 14 (87.5% of the total) had coating pore intercepts between 50 μm and 150 μm. The mechanical properties of the coatings were independent of the substrate material used. The shear and tensile strengths of the composite coatings with hydroxyaptite (HA) were significantly lower than those of the pure metal coatings. Conclusions For the design and manufacture of artificial joints with porous coatings, the performance of the coating can be referred to the following indexes: the coating thickness is 300－500 μm, the coating porosity is 30%－50%, the coating pore intercept is 50－150 μm. The substrate materials can be selected based on the use of the product. The effects of a lower bonding force on product performance should be considered when designing prostheses with composite coatings containing HA. This range of performance metrics provides control for long-term clinical extraction analyses.
