Year: 2014
Type: dissertation
Study design: Observational Study
Abstract: Total hip replacement (THR) is an efficacious, reliable, and cost effective procedure for reconstruction of hip joints. Aseptic loosening is one of the most significant long-term complications of THR. The aetiology is multifactorial. Both biological and mechanical factors seem to play important roles in aseptic loosening. The formation of a synovial-like membrane between prosthesis or cement and bone is a common pathologic finding in aseptic loosening. The hypothesis in this study was that cytokines, which stimulate bone formation, are decreased in interface tissue (IT) in patients with loose THR compared to control synovial membranes. In this study, the histopathological features of IT were found to be very similar to synovial tissue from OA. However, particulate debris and macrophages/ foreign body giant cells were found in most ITs. Immunohistochemical staining showed up-regulated expression of bFGF, PDGF, TGF-ß1 and TGF-ß2 in interface and pseudocapsular tissues but down-regulated expression of IGF-I in the same areas. IGF-II was down-regulated in pseudocapsular tissues. Expression of BMP-2, -4, -6 and 7 as well as VEGF and its receptors 1 and 2 was similar in ITs when compared to control samples in general, but expression of BMP-4 and VEGF receptor 1 was up-regulated in IT macrophage-like cells and VEGF receptor 1 and 2 also in IT fibroblast-like cells. The cells of origin of these cytokines were macrophages, fibroblasts, and endothelial cells. This study clarified the cytokine spectrum found in interface and pseudocapsular tissue around loose THR. The results do not support the hypothesis that bone formation enhancing cytokines would be consistently decreased in these tissues. All of the studied cytokines can induce scar tissue development and many of them also blood vessel formation, tissue inflammation and some even enhance osteoclastic bone resorption. They most probably have mixed positive and negative effects on implant-bone fixation in the course of aseptic loosening of THR, depending on multiple factors like local concentration of different cytokines, cell-cell contact modulation, periprosthetic tissue (PT) hypoxia and pH, implant micromotion, and systemic factors such as hormones. Despite improving implant technology, it is unlikely that particulate debris and loosening can be completely eliminated. Therefore, additional studies are necessary to elucidate the complex cytokine network in the context of aseptic loosening. Through further understanding of these aseptic loosening processes, it may be possible in the future to modulate or prevent cytokine expression or their effects immunologically or pharmacologically.
Source: Työväentutkimus Vuosikirja
Author: Ville Waris
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1536759641