Strength of the cement-bone interface relies more on interface contact than cement penetration depth

In cemented total hip arthroplasty, the implant needs a mechanically stable cement-bone interface for its survival. This can be achieved by adequate cement penetration into the bone lacunar and trabecular spaces.
Many studies have been conducted to investigate the strength of the cement-bone interface in relation to the amount of cement penetration, but mainly on a macro-scale [1]. However, to gain a more detailed insight into the mechanical aspects of this geometrically complex interface, the cement-bone interface should be studied on a micro-scale. We developed micro Finite Element (FE) models of the cement-bone interface and varied the cement penetration depth. Subsequently, we loaded the FE models until failure and asked the following questions: (1) Is there a relationship between penetration depth, contact area and strength?; (2) Is the interface stronger in shear than in tension?; (3) How valid are the FE models compared to experimental findings?