Effects of Region-Specific Material Properties of Patellar Tendon on the Magnitude and Distribution of Local Stress and Strain

The effects of the region-specific material properties of the patellar tendon (PT) on the magnitude and distribution of local stress and strain are poorly understood. Hence, this study investigated this issue using finite element analysis. A three-dimensional PT model was developed based on parameters obtained from previous studies, and was bisected in the frontal plane. Two models were created: one that considered region-specific material properties (two-material model) and one that did not (one-material model). An 8% strain was applied to the proximal surface, and the mean and peak first principal stress and strain were calculated. In the two-material model, the mean first principal stress observed in the anterior region was 28.5% higher than that in the posterior region. However, in the one-material model, the mean first principal stress in the anterior region was 19.5% lower than that in the posterior region. Focusing on the differences between the models, the mean and peak first principal stresses in the posterior region of the one-material model were 61.1% and 41.2% higher, respectively, compared with those in the two-material model. Furthermore, the mean and peak first principal stresses in the proximal and distal regions of the posterior region in the one-material model were 41.8-75.8% higher than those in the two-material model. These results suggest that the region-specific material properties of PT influence the stress distribution and underscore the importance of modeling that incorporates region-specific material properties in PT finite element models.