Impact Response Analysis of Patella-Patellar Tendon-Tibial Tuberosity Complex

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Attenuation of impact load through patella-patellar tendon-tibial tuberosity (PTT) complex has been investigated with respect to the progress of ossification of growing cartilage in tibial tuberosity. Materials used in this study were PTT complexes and patellar tendons taken from porcine hind legs with three different stages of ossification of tibial tuberosity. Their stages of ossification were represented by body weight (20,100 and 200kgf). Impact tensile tests on PTT complexes and patellar tendons were performed at room temperature using the split-Hopkinson pressure bar technique. In both tests on PTT and patellar tendons pretensile loads were applied to them just before an application of impact load. The experimental load transmission ratio of PTT complexes increased with an increase of pretension, independent of body weight. Larger body weight, or highly ossified specimen appeared to show lower load transmission ratio. Significant change in Young's modulus of patellar tendon with … More an increase of pretension as well as the progress of ossificationt of growing cartilage in tibial tuberosity was not found. Since material properties and geometry of each section of the complex were considered to be varied with its growth, the impact responses of PTT complexes with different stages of ossification were theoretically analysed with the consideration of attenuation property of stress wave for the prediction of load transmission ratio as well as the section subjected to maximum strain. To this end, simple models representing mechanical behaviour of the complexes were made with the assistance of their X-ray images and BMD measurements, and the analyses were performed based on the one-dimensional wave propagation theory. Static analyses of the same models as used in the impact response analyses were also performed. The impact response analyses well predicted the location of injuries in different stages of growing process, while static analyses could not predict such clinical situation. Less