A comparison study was implemented for a generic orthopedic implant (GOI) in the ASTM and the elliptical phantom, and in a homogeneous and heterogeneous Duke model in terms of RF induced heating. The study aimed at the necessity of choosing reliable parameter for comparison purposes in phantom and human model simulations in order to reduce the uncertainty of heating effects. The GOI was selected from a product matrix given in [1] as the test target and was evaluated within comprehensive numerical simulations.The GOI was placed at a distance of 20 mm from the ASTM and elliptical phantom wall and at the center of the gelled saline medium [2] in sagittal axis as the longitudinal axis of the GOI was placed at homogeneous E-field [3] area [4][5] while the orientation of the implant was kept to be clinically relevant in respect to the tangential E-field as much as possible. Thereafter, the GOI was implanted into the hip bone of the homogeneous (for comparison reasons) and heterogeneous Duke phantom from the Virtual Family [6], where the temperature rise was retrieved from comprehensive multi-physics numerical simulations. The numerical analysis involved full-wave 3D EM simulations followed by corresponding thermal simulations within all four mentioned environments. The implant was numerically exposed to the RF fields using the numerical model of the Medical Implant Test System MITS 1.5 (Zurich MedTech, Switzerland), Figure 1. The simulations were carried out with the SEMCAD X V14 (Schmid & Partner Engineering AG, Switzerland) FDTD simulation platform [7]. The phantoms and the Duke model were placed inside the coil at the position at which the GOI was located at the center of the coil in longitudinal axis. However there is no guaranty that the simulated landmark position is the worst clinical case.The vector electrical field profile of all four phantoms without the GOI is shown in Figure 2. The GOI has been placed in this image to show the implantation area respect to the background E-field. The tables of results (Figure 5) shows the 0.1-, 1-, 5- and 10- gram-averaged SAR at the tip of the stem and the tip of the screw, where the hotspot was expected to occur (shown in Figure 3 for the ASTM phantom). The table also shows the maximum electric field E_rms at the surrounding tissue of the screw and the stem as well as the result of the thermal simulations in different media with the 2 W/kg whole body averaged SAR based on ASTM F2182-11a [2] after 900 seconds exposure. Although the maximum SAR_5g and SAR_10g in the ASTM and the elliptical phantom were located at a different spot in comparison to the maximum SAR_0.1g and SAR_1g, the thermal simulations showed that the maximum temperature rise appeared at the tip of the screw in the ASTM phantom and tip of the stem in the elliptical phantom as shown in Figure 4. Regarding the more relevant clinical cases of homogeneous and heterogeneous Duke model, the EM and thermal simulations using the same exposure test setup, showed the same appearance of hotspots at the same locations for all evaluated cases.The location of hotspot for a GOI under test was varying for different mass averaged SAR in the ASTM and the elliptical phantom, but was consistently located at the tip of the screw in the two human phantoms. Therefore, in order to locate the hotspots, limiting the comparison to averaged SAR over only one specific mass within EM simulations could lead to a misinterpretation in the location of the hotspots. However, considering the uncertainty of the radio frequency heating test in simplified setups (like ASTM and elliptical phantoms in this case study), simulations with a human phantom including the GOI could increase the degree of reliance while reducing uncertainty.