Current concepts review: symmetry versus asymmetry in the design of total knee femoral components--an unresolved controversy.

Despite the excellent success of earlier total knee replacement designs such as the Total Condylar Knee (Johnson & Johnson, Raynham, MA), which had a symmetrical femoral component, the majority of modern designs feature a more anatomic and asymmetric femoral prosthesis. A raised lateral phalange, an angled trochlear groove, or both are thought to improve patellar tracking. Laboratory studies, however, suggest that surgical technique may be the dominant factor in determining patellofemoral kinematics. Component design has not been proven to be significant. A prosthesis with asymmetric femoral components may cost more. The literature reviewed in this article finds no advantage to the use of asymmetric versus symmetrical femoral components in total knee replacement.