The past two decades have seen many technological improvements in the science of knee replacement. The problems that orthopedic surgeons faced when choosing a knee replacement device were different in the 1980s than they are in 2000. Another problem that orthopedic surgeons faced when performing TKR lay in the prosthetic design.
Prosthetic constraint transmits excessive force to the prosthesis fixation interface.
Instrumentation and surgical techniques were improved in the following decade, and orthopedic surgeons experienced dramatic reductions in malalignment, instability and loosening of the replacements. Knee replacement design was based on a less-constrained model that had a wider range of motion, which further reduced the incidence of loosening. Additionally, reducing the amount of implant constraint meant less control over knee kinematics. 1 Anterior shifting on the femur increased the potential of polyethylene wear. Blunn and Walker performed a laboratory simulation on how polyethylene wears in different situations.