Sources of osteolysis around total knee arthroplasty: wear of the bearing surface.

Once mostly a problem in total hip arthroplasty, osteolysis has now emerged as a significant problem around total knee arthroplasty (TKA). The development of osteolysis is often related to wear of the polyethylene bearing surface with production of biologically active particulate debris. There are many structural and design factors related to the polyethylene bearing surface that have been shown to affect the extent of wear that occurs over time. For instance, the processing, manufacturing, and sterilization methods of polyethylene all are critical factors in determining its mechanical and wear-resistant properties. Cross-linking of polyethylene bearing surfaces in TKA, however, may not demonstrate the same degree of improved resistance to wear as seen in total hip arthroplasty. Optimization of polyethylene bearing surface thickness, with a goal to insert at least 8 mm of polyethylene, has been shown to minimize contact stresses and subsequent fatigue failure of total knee implants. Selecting a well-designed component with minimal counter surface roughness is also important in minimizing the generation of polyethylene wear debris and subsequent osteolysis. Finally, proper surgical technique, including restoration of mechanical axis and rotational alignment, is critical to minimizing wear and maximizing the longevity of TKA.