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General discussion 34513In vivo analysis – Tribological resultsHaving implemented the data that was gathered during the literature analysis in the design of a novel custom-made total TMJ prosthesis, an animal model experiment was conducted to evaluate its suitability for human implantation. A sheep model was opted for, as they are considered the gold standard in large animals.(88,89) As they spend 4 hours per day eating, and 8 to 9 hours per day ruminating at rate of 128 and 100 mastication cycles per minute on average respectively, an evaluation period of 288 days equals 22 human years of masticatory function, thus allowing for a proper tribological evaluation.(90,91)Both a linear and volumetric analysis of the amount of wear of the UHMWPE-component of the fossa was performed. Linear wear (mm/year) is used in orthopedic surgery to determine the lifecycle of an implant and thus providing information within how much time after implantation, the fossa component needs to be replaced. With an average linear wear of 0.67 ± 0.28mm days for the coated system and 0.88 ± 0.41mm for the uncoated prosthesis, which converts to respectively 0.03 ± 0.01mm/year and 0.04 ± 0.02mm/year, the custom-made TMJ prosthesis outperformed both total hip implants (0.08-0.2mm/year) and total knee prostheses (0.05-0.23mm/year).(92) This is of significant importance, as the risk of periprosthetic osteolysis increases if the amount of linear wear is higher than 0.1mm/year.(93) In addition, a volumetric wear analysis was performed to determine the total amount of lost UHMWPE volume. This is of importance as the risk of periprosthetic osteolysis remains rare if the wear volume remains below 80mm³ per year. (94) With an average volumetric wear of 25.29 mm³ ± 11.43mm³ and 45.85mm³ ± 22.01mm³, which converts to 1.15 ±0.52mm³/year for the coated TMJR and 2.08 ±1.00mm³/year for the uncoated system, the TMJR outperformed both the total hip and knee replacement in this field as well.(95)One of the shortcomings in our research on the wear analysis of the UHMWPE component was the inability to register the fossa component prior to implantation. Due to logistical constraints and the need to maintain the implant's sterility, we used the implant design render instead of the actual printed component. In future analyses, whether in Nikolas de Meurechy NW.indd 345 05-06-2024 10:15