Mathematical study on the guidance of the tibiofemoral joint as theoretical background for total knee replacements

作者：Fiedler Christoph; Gezzi Riccardo; Frosch Karl Heinz; Wachowski Martin Michael; Kubein Meesenburg Dietmar; Doerner Jochen; Fanghaenel Jochen; Naegerl Hans

来源：Acta of Bioengineering and Biomechanics, 2011, 13(4): 37-49.

• tibiofemoral joint
• design of TKR
• instantaneous rotational axis
• slip ratio
• joint force distribution
• force wrench
• four-bar linkage

The mathematical approach presented allows main features of kinematics and force transfer in the loaded natural tibiofemoral joint (TFJ) or in loaded knee endoprostheses with asymmetric condyles to be deduced from the spatial curvature morphology of the articulating surfaces. The mathematical considerations provide the theoretical background for the development of total knee replacements (TKR) which closely reproduce biomechanical features of the natural TFJ.
The model demonstrates that in flexion/extension such kinematic features as centrodes or slip ratios can be implemented in distinct curvature designs of the contact trajectories in such a way that they conform to the kinematics of the natural TFJ in close approximation. Especially the natural roll back in the stance phase during gait can be reproduced.
Any external compressive force system, applied to the TFJ or the TKR, produces two joint reaction forces which - when applying screw theory - represent a force wrench. It consists of a force featuring a distinct spatial location of its line and a torque parallel to it. The dependence of the geometrical configuration of the force wrench on flexion angle, lateral/medial distribution of the joint forces, and design of the slopes of the tuberculum intercondylare is calculated.
The mathematical considerations give strong hints about TKR design and show how main biomechanical features of the natural TFJ can be reproduced.

• 出版日期2011