Researchers from Charité — Universitätsmedizin Berlin observed in detail how different metals are released from joint implants and accumulate in the surrounding bone tissue. Their findings suggest a steady release of metals from various implant components.

In contrast to previous assumptions, this was not related to the degree of mechanical stress involved.

The researchers’ findings, which have been published in Advanced Science, could help to optimize the materials used in implants and enhance their safety, they suggest, in a media release.

To study the spatial distribution and local toxicokinetics of metallic wear and corrosion products within the surrounding bone tissue, the team — led by Dr Sven Geißler of Charité’s Julius Wolff Institute for Biomechanics and Musculoskeletal Regeneration and BIH Center for Regenerative Therapies — used a unique synchrotron-based X-ray fluorescence imaging setup.

“Our work has enabled us to show, for the first time, that both particulate and dissolved metals released from arthroplasty implants are present in the surrounding bone and bone marrow at supraphysiological levels. Therefore, the collagen-rich layer which encapsulates the implant after surgery does not separate these metals from human tissue to the extent previously assumed.”

— Dr Sven Geißler

The team collected minute bone and bone marrow samples from 14 patients undergoing either a hip or knee arthroplasty procedure. They then determined the qualitative and quantitative composition of the samples using a technique known as x-ray fluorescence, which provides unique insights into the concentration, distribution, location and accumulation of metallic degradation products like cobalt, chromium or titanium in adjacent bone and bone marrow.

The extremely bright and intensively focused x-ray beam required was achieved by the synchrotron radiation source at the European Synchrotron Radiation Facility (ESRF). The ESRF, which is located in Grenoble, France, is the only particle accelerator in the world to offer a spatial resolution of up to 30 nanometers, the release explains.

“Our study has made a major contribution to the improvement of the risk-benefit evaluation of medical devices. It has shown that these evaluations should not only comprise biocompatibility testing of raw materials; rather, biocompatibility testing should also extend to wear and corrosion products. The data from this study will therefore prove instrumental in keeping implant safety at the highest possible level.

— Dr Sven Geißler

Based on their findings, the researchers plan to conduct additional studies which will investigate the biological consequences of metal release on bones and bone marrow. At the same time, the researchers will develop new approaches which will facilitate the reliable preclinical testing of implant materials using both human cells and engineered tissues, they add, in the release.

[Source(s): Charité – Universitätsmedizin Berlin, Science Daily]

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