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Fig. 1 | BMC Musculoskeletal Disorders

Fig. 1

From: Model-based roentgen stereophotogrammetric analysis using elementary geometrical shape models: 10 years results of an uncemented acetabular cup component

Fig. 1

a Non-cemented titanium (TiAl6V4) acetabular cup component, composed of a cylinder attached to the rim of a spherical segment, covered by TiRC coating (Titan Rough Coating) with a surface layer thickness of approximately 300 μm, a surface roughness of Rz = 100–150 μm and four additional attached and pairwise-arranged tantalum markers for marker-based RSA measurements. This special RSA cup was in accordance with legal rules. b For model-based EGS-RSA approach, a hemisphere model with a curvature radius and implant height according to the technical drawings of the investigated cup component was generated. The local EGS model coordinate system was set to the centre of gravity. All axes were aligned perpendicular to each other. c Left image of an RSA reference radiographic image pair with three of four visible implant markers. Implant marker no. 4 occluded by the implant itself within the RSA image. d Occluded implant marker problem for marker-based RSA approach. Left image out of the same patient follow up series, with occluded implant markers no. 3 (x) and 4. As at least three implant markers were necessary for marker-based RSA approach, for this RSA image pair a migration calculation was not possible

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