Biomechanical analysis of knee flexion and extension

For the knee, mathematical analyses for the sagittal plane were performed on data obtained from roentgenograms and a load cell incorporated in a specially constructed force table. Normal knees from 26 subjects were examined. Some of the results were: (1) the axis of rotation for the knee displaced 3·2 cm through a 90° range and is located at the level of the lateral femoral epicondyle, (2) the moment arm is greater for knee extensors than the flexors, (3) the maximum average torque values of nearly 1200 kg-cm result from eccentric (lengthening) and isometric (static) muscle contractions while the isometric (static) flexor contraction near complete extension produced a maximum average torque of 636 kg-cm. and (4) during muscular efforts against external load the contact forces at the patello-femoral and tibialfemoral joints varied from 0·38 to 3·40 times body weight.