A novel total knee replacement by rolling articulating surfaces. In vivo functional measurements and tests.

The purposes of the paper were as follows: to show the fundamental functional differences between the natural knee and common total knee replacements (TKR), to describe the ideas on how main properties of the natural knee can be adopted by a novel TKR and to present some main biomechanical functions of this TKR. By analyzing the morphology of the articulating surfaces and the kinematics of the natural knee the design of the novel TKR was developed. The use was made of the test procedures established in vitro and of lateral X-ray photographs as well as fluoroscopy in vivo. The function of the novel TKR is comparable to that of the natural knee joint in terms of kinematics (roll/slide behaviour), loads of the articulating surfaces (diminished shear loads), stability and leeway under external impacts, reduction of the load in the patellofemoral joint, and ligament balancing.