Loosening of metal implants due to particle exposure of the surrounding tissue is one of the main reasons for renewed surgery and replacement of the endoprosthesis of the hip or knee. The exact role of these metal particles leading to non-bacterial inflammation is still controversial. Among other things, it is suspected that the metals undergo chemical changes and accumulate behind an isolating peri-implant membrane in the surrounding bone and bone marrow. Synovial tissue close to the prosthesis forms secondarily after implantation. (The synovialis or synovial membrane is a specialized mucous membrane that lines the inside of the articulations, tendon sheaths and bursae. it secretes the joint mucus).

For their investigations, scientists from the Julius Wolff Institute of Charité - University Medicine, the Berlin Institute of Health, Center for Regenerative Therapies, and from the Technical University of Berlin used the HUMIMIC Chip2 from TissUse GmbH. Human mesenchymal stem cells were isolated from bone marrow samples of affected patients. After a subsequent procedure, the cells were used and cultured for a bone and bone marrow 3D culture. In the microfluidic HUMIMIC Chip2 the bone/bone marrow model was exposed for 20 days to bivalent cobalt and trivalent chromium via the medium. Afterward, X-ray fluorescence analyses and various microscopic examinations were performed.

The researchers were able to show that different metals from implants are found in the surrounding bone and bone marrow. The investigated elements chromium, cobalt, and additionally titanium were found preferentially in different regions of the bone marrow.

The spatially resolved element analyses in the micro- and nanoscale performed in this study provide important information on the concentration, distribution, location, and accumulation of metallic degradation products in peri-implant bone and bone marrow. The results give important indications of localized degradation and corrosion developments.

The scientists are convinced that not only the issue of biocompatibility should play a role in the risk-benefit assessment of such medical devices, but also possible abrasion and corrosion behavior.  


Original publication:
Schoon J et al (2020). Metal-specific biomaterial accumulation in human peri-implant bone and bone marrow. Adv Sci (2020), DOI: 10.1002/advs.202000412

Another source:
https://idw-online.de/de/news?print=1&id=752464