A variety of surface modifications including porous coatings, grit blasting, plasma spraying, and hydroxyapatite coating has been used to enhance implant fixation.
Bone ingrowth into a porous coating has demonstrated durable fixation for a multitude of cementless stem designs. Porous coatings have historically been created by either beads or fiber mesh (Fig. 371A and B) applied to the stem by sintering or diffusion bonding processes. Highly porous metals such as tantalum were initially utilized for cementless fixation of acetabular components but have more recently been applied to femoral stems also (see Fig. 371C).
Types of bone ingrowth surfaces. Traditional surfaces produced from sintered beads (A) and diffusion bonded fiber mesh (B). C, Newer highly porous tantalum more closely resembles structure of trabecular bone. (A courtesy of Smith & Nephew,
Memphis,TN? B and C courtesy of Zimmer, Warsaw, IN.)
Bone ongrowth implies growth of bone onto a roughened (albeit nonporous) surface. Ongrowth surfaces are created by grit blasting or plasma spray techniques. Grit blasting involves the use of a pressurized spray of aluminum oxide particles to produce an irregular surface ranging from 3 to 8 μm in depth
Plasma spray techniques use highvelocity application of molten metal onto the substrate in a vacuum or argon gas environment and produce a
highly textured surface (see Fig. 37-2B).
Heating of the implant is not required, and, consequently, there is little reduction in fatigue strength compared with the application of porous coatings. Hydroxyapatite can also be applied to implants by plasma spray (see Fig. 37-2C).
The thickness of the coating is typically 50 to 155
Types of bone ongrowth surfaces. (A) Gritblasted surface. More highly textured plasmasprayed surfaces: titanium (B) and hydroxyapatite (C). (A courtesy of Zimmer,Warsaw, IN? B courtesy of Biomet Orthopedics, Warsaw, IN? C courtesy of Stryker Orthopaedics,Mahwah, NJ.)
JUST provides 3 kinds of surface options
1.Ti+HA double coating
On one hand, porous surfacedimplants can enhance bone ingrowth as compared to dense implants in vivo. On the other hand, HAcoated implants stimulate the early bone formation onto the implants, as compared to noncoated
implants in vivo, and HAcoated porous implants enhance bone ingrowth as compared to porous implants.
JUST products with Ti porous and HA double coating
2.Vacuum plasma sprayed coating.
VPS is an indispensable method to produce highfunctional coatings for various advanced technologies. Plasma spraying Plasma spraying Plasma is an electrically conductive gas containing electrically charged particles, ions and electrons. In plasma spraying process, metals, alloys, high meltingpoint
materials, such as ceramics and cermets in powder or wire form are melted and sprayed onto the subjects. Plasma spraying has 2 types of methods, APS and VPS. APS is carried out in the atmosphere, and for VPS, in the chamber of which atmosphere and pressure are controlled.
Process flow chart of VPS
3.Atmosphere plasma sprayed coating.
JUST products of VPS and APS
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