To evaluate motions and joint reaction forces of the total knee prosthesis during deep knee flexion such as kneeling and sitting straight, a simulator that reproduces the passive motion of the knee has been developed. The main feature of the simulator is that the knee joint is accurately and repeatedly moved from 0° to 180° flexion angle in six degrees of freedom. Moreover, the tibiofemoral and patellofemoral motion and joint reaction forces can be continuously measured. Assuming that muscular force is mainly generated with a quadriceps femoris muscle, the similar force vector is produced by two motors. The custom-designed posterior stabilized type total knee prosthesis which can be flexed to 180° has been inserted in the bone model and used for the evaluation. As a result, it was confirmed that this simulator was able to measure the motion and joint reaction force of the knee with high repetition accuracy. The experimental results showed the same tendency with those in the previously performed cadaveric experiment until 120° flexion. Hereafter, cadaver knee can be used for the evaluation of the knee prosthesis using the proposed simulator with high accuracy.

Keywords

Deep Knee Flexion, Knee Simulator, Passive Motion, Total Knee Prosthesis, Joint Reaction Force

Paper information

Yasuju TAKANO, Masaru UENO, Kazuo KIGUCHI, Syuya IDE, Masaaki MAWATARI and Takao HOTOKEBUCH, “Development of a Passive Knee Motion Simulator to Evaluate Deep Knee Flexion of Total Knee Prosthesis”, Journal of Biomechanical Science and Engineering, Vol. 4, No. 4 (2009), pp.562-575 . doi:10.1299/jbse.4.562

The objective of this study is to analyze kinetics and kinematics of artificial knee joint at deep flexion, using a 2D geometric model. Our knee model was composed of the tibio-femoral and patello-femoral joints, including the patella tendon and the quadriceps muscles. Since the model was 2D, it neglected the rotation and the varus/valgus motion. In the model, such assumption was made that articulation surfaces were rigid and a point contact was made. Also it was assumed that the force and moment equilibrium conditions were always satisfied. The motion to be studied was decided as the motion from standing to deep squatting with heel-rising. From the simulation we found such results that the femur did not make a rollback and contact force at post-cam became pretty large in high and deep flexion, indicating the post-cam mechanism did not function well. Also patello-femoral contact forces reached larger than tibio-femoral contact forces. Our results demonstrated that how to design the post-cam and patello-femoral joint should be critical issues for developing a new prosthesis which can make deep flexion.

Keywords

Artificial Knee Joint, Deep Knee Flexion, 2D Model Analysis

Paper information

Michihiko FUKUNAGA, Tadasuke KATSUHARA, Shunji HIROKAWA, Masaaki MAWATARI and Takao HOTOKEBUCHI, “A 2D Model Analysis of Artificial Knee Joint during Deep Squatting”, Journal of Biomechanical Science and Engineering, Vol. 4, No. 2 (2009), pp.298-305 . doi:10.1299/jbse.4.298