Impact wave transmission through the lower skeletal extremity

Previous studies have revealed that strong relationships do exist between articular cartilage deterioration and prolonged exposure of the joint to impulsive mechanical stress. However, the phenomena of impact wave transmission through the human skeletal system is, at present, not fully understood. This study is an attempt to determine the impact wave propagating properties of the lower skeletal extremity, i.e., the tibia, knee joint, and femur. An abbreviated (cut at the lower tibia and upper femur ends) cadaveric lower extremity is suspended vertically by long steel wires. The upper femur end is subjected to a 150‐lb load (to simulate body weight) and the lower tibia end rests on a 100‐lb shaker. The skeletal system is subjected to a 3‐g impulsive load at a frequency range of 1–3 Hz to simulate walking and jogging. Preliminary results revealed that impact wave propagation speed varies significantly at different portions of the skeletal system, and that the subchondral region of the knee joint attenuates the impact stress drastically by approximately 50%. The effect of total knee prosthesis, shoe inserts, in the propagation of impact wave is also being investigated.