Print Page Email to Friend

ADVANCE® Double-High Knee

The ADVANCE® Double-High Knee is designed to provide increased stability⁴⁹ and allow higher flexion⁵⁰ than traditional cruciate-retaining (cr) knees. The medial side of the tibial insert features an anterior lip that measures 10mm in height from the deepest point of the articular surface in all sizes and 23-32mm in length, depending on component size (Figure 12A).

Designed to provide anterior stability and prevent posterior tibial subluxation, the anterior lip resists the paradoxical motion prevalent in traditional CR knees.^45,46,47 This non-kinematic paradoxical motion (or anterior femoral sliding) has been shown to reduce flexion by causing early posterior tibio-femoral impingement. It is also theoretically responsible for placing increased stresses on the PCL and increasing tibio-femoral sheer stresses. By reducing the effect of paradoxical motion, the ADVANCE® Double-High Knee may allow increased flexion and protect the PCL from uncharacteristic stresses. To enhance the ability to reach deep flexion, the anterior lip inhibits the femur from sliding forward beyond the posterior third of the tibial surface. This maintains a mechanical advantage by sustaining a long quadriceps lever arm.

Finally, to maximize the effect of the PCL on flexion, the postero-medial articular surface is directed in the anatomic path of PCL function. As for the lateral surface, it features a wide, arcuate path designed to allow 15 degrees of tibio-femoral rotation from any point on the medial side. This, combined with the anterior stability and posterior path of the medial side, allows the PCL to direct the femur into the necessary rotation and translation necessary to achieve natural, deep flexion (Figure 12B).