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Surface Coating for Press Fit Femoral / Acetabular Components:

- Discussion:
    - see bone ingrowth 
    - most important factor for initial success of cementless THR;
    - reduces micromotion between implant and bone along entire length of implant;
    - pore size:
            - porous ingrowth surfaces w/ beads or wires that create pore-interconnection sizes in range of 150-400-  micrometers are optimum;
            - references: Biologic fixation of porous-coated implants.        
    - types of coating surfaces: 
         - titanium beads; 
         - sintered beads; 
         - hydroxyapatie coating
                - the outcome studies on this have generally been poor, with the exception of hydroxyapatite threaded implants;
                - in the study by Manley et al 1998, 11% of hydroxyapatite cups had been revised by 5 years;
                       - these authors concluded that the hydroxapatite surface could not stand the tensile forces at the cup bone interface;
                       - it is important to point out that 99% of threaded hydroxyapatite cups were stable at 5 years; 
         - grit-blasted surfaces:
                   - process textures the metal surface with a pressurized spray of aluminum oxide grit or stainless steel shot which creates an irregular surface (between 3-8 micrometers in depth); 
          - titanium plasma spray: (see titanium)
                   - plasma spray can be applied to the implant without having to heat the implant (less weakening); 
                   - titanium exposed to air/blood creates a titanium oxide surface conducive to bone ingrowth;
                   - the rougher the surface, the greater the surface area for creation of titanium oxide layer;
                   - goal after fixation is creation of increased bone density along the stem;
                   - references:
                         - Plasma spray-coated Ti femoral component for cementless total hip arthroplasty.
                         - Press-fit stability of uncemented hemispheric acetabular components: a comparison of three porous coating systems.
                         - Effect of circumferential plasma-spray porous coating on the rate of femoral osteolysis after total hip arthroplasty.
                         - Osseointegration of sintered porous-surfaced and plasma spray-coated implants: An animal model study of early postimplantation healing response and mechanical stability. 
                         - Influence of various structure treatments on histological fixation of titanium implants.
                         - Primary cementless hip arthroplasty with a titanium plasma sprayed prosthesis.

- references: 

The influence of surface-blasting on the incorporation of titanium-alloy implants in a rabbit intramedullary model. 

Biologic fixation of porous-coated implants

         - Cementless total joint arthroplasty prostheses with titanium-alloy articular surfaces. A human retrieval analysis.
         - Clinical performances of ingrowth surfaces.
         - Primary total hip reconstruction with a titanium fiber-coated prosthesis inserted without cement
         - The influence of surface-blasting on the incorporation of titanium-alloy implants in a rabbit intramedullary model.
         - Periprosthetic bone loss in total hip arthroplasty. Polyethylene wear debris and the concept of the effective joint space.

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Clifford R. Wheeless, III, MD on Sunday, August 18, 2013 5:50 am