RESUMEN
BACKGROUND: The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination. METHODS: The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles. RESULTS: All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis. CONCLUSIONS: The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.
RESUMEN
Occupational and environmental exposure to Co and Cr has been previously linked to a wide array of inflammatory and degenerative conditions and cancer. Recently, significant health concerns have been raised by the high levels of Cr and Co ions and corrosion products released by biomedical implants. Herein, we set to analyze the biological responses associated with Co and Cr toxicity. Histological, ultrastructural, and elemental analysis, performed on Cr and Co exposed patients reveal the presence of corrosion products, metallic wear debris and metal ions at varying concentrations. Metallic ions and corrosion products were also generated in vitro following macrophage phagocytosis of metal alloys. Ex vivo redox proteomic mapped several oxidatively damaged proteins by Cr(III) and Co(II)-induced Fenton reaction. Importantly, a positive correlation between the tissue amounts of Cr(III) and Co(II) ions and tissue oxidative damage was observed. Immobilized- Cr(III) and Co(II) affinity chromatography indicated that metal ions can also directly bind to several metallo and non-metalloproteins and, as demonstrated for aldolase and catalase, induce loss of their biological function. Altogether, our analysis reveals several biological mechanisms leading to tissue damage, necrosis, and inflammation in patients with Cr and Co-associated adverse local tissue reactions.