Cementless Surgery

Because of the increased loosening rates of cemented total knee replacements in the so called "high risk" patients, efforts have been made to develop a way to insert knee replacements without cement. In this country the most popular method has been to achieve fixation by "bone ingrowth". In this case a portion of the component is coated with a porous metal surface and fixation is achieved by bone growing up to and into the pores in the metal.

Animal research began in the mid to late 1970's and use in humans began in the early 1980's. Cementless total knee replacements have not been as successful as the cemented ones. It has been difficult to obtain ingrowth of bone into the tibias component. Mild to moderate pain of unknown cause has been reported in up to 20% of cases. Despite these problems, it still may be advisable to consider a cementless tibial component in patients who are under 50 years of age, or who are excessively obese (over 250 pounds). Cementless femoral components, on the other hand, have performed as well as cemented ones.

Current practice is to decide at surgery if a cementless femoral component can be used. This depends on the quality of the remaining bone and the accuracy of the bone cuts. If a cementless femoral component is used in conjunction with cemented tibial and patellar components, it is called a "Hybrid" total knee.