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  CHAPTER OUTLINE

  
  
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    Design 151

    
    
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    Ingrowth 151

    
    
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    Geometry 152

    
    
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    Surface and Coatings 152

    
    
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    Fixation 153

    
    
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    Interface 153

    
    
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    Indications 154

    
    
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    Technical Considerations 154

  
  

The first total hip arthroplasty was performed in 1938 in London more than 20 years before polymethylmethacrylate would be introduced as a bone cement. With the introduction of his cemented hip prosthesis in the 1960s, Charnley forever changed the future of total hip arthroplasty. Although the early results with cemented cups were excellent, it became clear with long-term follow-up studies that cemented acetabular components develop high rates of loosening and migration ( Table 18-1 ). The pathologic process involved in the loosening of cemented acetabular components came to be known as cement disease. Many in the field believed that cement represented the major obstacle to long-term fixation, and attempts were made to eliminate the use of polymethylmethacrylate in the hope that this would limit aseptic loosening.

It is clear that if an arthroplasty is to have durable long-term function it must develop a biologic and mechanical equilibrium with the host bone. In 1979, Morscher described several special requirements for an endoprosthesis to be fixed without cement. The first requirement is to create as small a defect as possible, such as to disrupt the physiologic biomechanics of the bone as little as possible. The design, stabilization, and mechanical properties of the prosthesis must take into consideration the forces acting on the system in all directions to avoid micromotion during physiologic loading of the implant. Lastly, the biologic nature of the bone should be respected, taking care to avoid excessive damage to the surrounding tissues during preparation and insertion.