Tensile bonding at bone-biomaterial interfaces. An in vivo test and related finite element stress analysis

Push-out tests subject an interface primarily, but not exclusively, to shear loading, and in any case, shear is not the sole loading mode expected at interfaces in vivo; normal components of tractions are also expected. Hence, it is also desirable to develop an accurate test of tensile bonding at bone-implant interfaces. Accordingly, we have developed the following in vivo experiment and finite element (FE) stress analysis. It is shown that multiaxial stress field exists at the washer-bone interface, with moderate stress peaks at the edges of the washer. While the predicted axial stress components vary along the interface, they do not differ greatly from the nominal axial stress. The radial and circumferential stresses were less than the axial stresses.