Ligament Strains Predict Knee Motion After Total Joint Replacement A Kinematic Analysis of The Sigma Knee

A passive forward kinematics knee model was used to predict knee motion of a total joint replacement. Given a joint angle, maps of articular surfaces, and patient-specific ligament properties, this model predicted femorotibial con- tact locations based on the principle of ligament-strain minimization. The model was validated by physical experiments on a commonly implanted knee prosthesis, showing excellent correspondence between the model and actual physical motion. Results suggest that the knee prosthesis studied required an intact posterior cru- ciate ligament to induce the desirable roll-back motion, and that a single-bundle model of major knee ligaments generated kinematics similar to that of a multi- bundle ligament model. Implications are that a passive model may predict knee kinematics of a given patient, so it may be possible to optimize the implantation of a prosthesis intraoperatively.