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Animal experiment: Surface wear analysis1395skull was retained. The rest of the sheep was disposed of. Next, the left side of the skull was skinned, and the neurocranium, left eye, and anterior maxillary and mandibular halves were removed. After three months of immersion in formalin 4%, the peri-articular tissues were resected for histological evaluation. The condyle was transected at the condylar neck by means of an Exakt 300 diamond band saw (EXAKT Technologies, Inc., Oklahoma, USA) at Morphisto Gmbh (Frankfurt, Germany). The fossa component was first clinically evaluated for its bony integration (e.g. if any macro-motions were seen or if a fibrous layer had formed between the implant and the bone) after which the screws were removed and the fossa was removed from the skull.With respect to the fossa, both linear and volumetric wear analysis of the articulating UHMWPE surface was performed by means of optical scanning. Linear wear, expressed in mm/year, is used in orthopedic surgery to determine the lifecycle of an implant. However, as it does not determine the total amount of UHWMPE volume that is lost, the volumetric wear, reported as mm³ per year, was evaluated as well. This is of importance, as it evaluates the total amount of debris that is formed and does not just evaluate the deepest point of material loss on the bearing surface. To determine the amount of linear wear, first a 3D scanner applying bluelight technology (ATOS CORE 135, GOM GmbH, Braunschweig, Germany) was used. The scanner was first calibrated according to the company prescribed calibration procedure, using a type CP40/170 calibration plate. This glass plate has circular markers with several markers having a larger diameter compared to the rest of the markers. These larger markers define the coordinate origin of the panel coordinate system. The 3D coordinates of the central points of each circular marker are measured, as well as distances between certain defined markers. This calibration process was performed and certified by a GOM-employed specialist, resulting in a 13µm accuracy. However, because this 3D scanner does not allow for evaluation beyond a depth of 1 mm, the linear wear of these samples was recalculated and confirmed using a LC60Dx laser line scanner (LLS) (Nikon Metrology NV, Leuven, Belgium) mounted onto an MC16 Coordinate Measuring Machine (CMM) (Coord3 S.r.l., Bruzolo, Italy) Nikolas de Meurechy NW.indd 139 05-06-2024 10:14