During the 80’s a new type of crash impact dummy, the rotationally symmetrical pedestrian dummy (RSPD), suitable for the assessment of car front aggressiveness in pedestrian impacts was developed (Aldman, 1985). This dummy enables measurement of biomechanical parameters, such as moments and forces et the knee joint level which ate related to the injury mechanisms.
To determine the ultimate resistance to shear force or bending moment of the human knee, it was desirable to make separate experiments, where only one of those two parameters affects the biological materiel et the time.
In this study an experimental method for assessment of the shearing force in the lateral direction et the knee joint her been developed. The maximum sheering force in the lateral direction the knee could beat without injuries war determined Injuries were described by measurements of the knee laxity and by dissection of the knee region.
Nineteen tests with human cadaver legs were carried out under dynamic conditions, nine at a velocity of 15 km/h and ten at 20 km/h. The results show the necessity of discussing two different injury mechanisms.
The first injury mechanism, which occurs et about 6 milliseconds after impact, is directly correlated with the force generated by the local acceleration of the biological system. The consequences of this force are injuries at the contact point and extra-atticulet injuries. The mean peak force correlated with this injury mechanism was 180 (i38) daN for an impact velocity of 15 km/h and 257 (±45) daN for an impact velocity of 20 km/h.
The second injury mechanism, which ocours at about 15 - 20 milliseconds tir impact is correlated with the force transfemed through the knee joint when the thigh was accelerated. The consequences of this force are intra-articulat injuries of the knee joint. The mean peak force correlated with this injury mechanism was 257 (±37) daN et impact velocity of 15 km/h and 322 (f46) daN et impact velocity of 20 km/h.