Porous ongrowth surfaces alter osteoblast maturation and mineralization.

Implant fixation through osseointegration is essential for the success of uncemented total joint arthroplasty, and nature and composition of implant surface play a critical role in this process. Despite widespread use of uncemented implants, the extent of bone ingrowth into implants is generally only a small percentage of the total implant surface. An understanding of the processes whereby bone cells grow into and multiply on porous surfaces is critical for the design and manufacture of implants that maximize ingrowth and implant fixation.

Metal ions activate vascular endothelial cells and increase lymphocyte chemotaxis and binding.

Metal on metal articulations in hip arthroplasty offer advantages, including lower volumetric wear compared to conventional metalonpolyethylene bearings, and increased resistance to dislocation. Reports described early failures, with histologic features similar to a Type IV immune response. Mechanisms by which metal wear products cause this reaction are not completely understood.