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Animal experiment: Inflammatory cell response evaluation1736the drained fluid yielded no results. Histopathological evaluation revealed the presence of both macrophage and a lymphocytic response (limited to less than 20% of the sample surface), but no polymorphonuclear leukocytes were found. Given the negative microbiological diagnosis, together with the absence of polymorphonuclear leukocytes, as well as the absence of abscess formation, we concluded no prosthetic joint infection or Type II reaction occurred.(12,16) Instead, post-mortem radiological evaluation revealed that the fossa component had been luxated. This was probably caused by the chosen screw diameter. This was similar to that in humans, whilst a larger diameter would have provided better fixation. The event of the luxation of the fossa component may well have led to the hematoma formed. Although no wear-induced ‘neo-synovitis’ was found, we did find a significantly increased amount of lymphocytes in the uncoated TMJR tissue samples compared to both the coated TMJR and the control tissues. This suggests that a chronic inflammatory response, or at least more chronic inflammation, was present in the uncoated TMJR group. This is important, as studies by both Hobza et al.(17) and Lohmann et al.(18) have shown that higher tissue concentrations of metals resulted in a higher lymphocytic infiltration. Their findings are consistent with ours, as less wear was found in the coated system compared to the uncoated system. Whilst we have not focused on implant integration and the interface between implant and bone in this paper, previously published studies have shown good histological results regarding bone ingrowth into the implant surface, thus no type V or VI-reactions were seen. The intracapsular material that was encountered during the dissection, was similar to the discovery by Van Loon et al.(19), during their sheep experiment. Although they hypothesized this were clusters of degenerated erythrocytes, we hypothesized that this brown material was a remnant of the hemostatic gelatin sponge (Spongostan, Ethicon, New Jersey, USA) placed in each of the intracapsular spaces during implantation. Nikolas de Meurechy NW.indd 173 05-06-2024 10:14