Mechanical properties of normal and pathological human patella

In order to understand the mechanical properties of human patella, regional differences of viscoelasticity and compressive strength have been investigated in normal and pathological human patella by viscoelastic spectrometer and a testing machine of the Instron type. In the normal human patella cancellous bone, the averaged compressive elastic modulus at the lateral side was 417.2 MPa and that at the medial side was 243.3 MPa. Comparing normal and pathological patella, we find that the normal patella stiffness and tan δ value were higher than the pathological ones. This fact implies that the normal patella is stiffened as a result of functional adaption.