The Model Analysis of Lower Limb at Ascending from Deep Knee Flexion

A new type of knee prosthesis capable of making deep knee flexion has been long awaited for Asian and Muslim people. Our research group has developed the prosthesis possible to attain even sedentary sitting and designated it as CFK (Complete Flexion Knee). In order to assess the performance of CFK, we have set up various kinds of simulation or experimental projects, such as a cadaveric study, a mathematical model analysis, a photoelastic analysis and FEM analysis. For carrying out the above-mentioned projects, we faced the most fundamental problem; the information about the forces acting on the joints has been limited for ambulatory activities but not for squatting or sedentary sitting. The objective of this study is to introduce the force acting on the knee joint at deep knee flexion through a 2D mathematical model simulation and some experimental measurements. Double leg ascending motion and single leg ascending motion from kneeling position were studied for 10 healthy male subjects. The results demonstrated that for double leg ascending, the maximum knee joint forces were 4.9±0.5 times of body weight, and for single leg ascending, the maximum knee joint forces of dominant leg were 5.0±0.2 times of body weight and those of supporting leg were 3.0±0.5 times of body weight. Ascending speeds did not affect the results much as long as the motion was not strenuous like jumping up/down.