Synchrotron-based characterization of arthroprosthetic CoCrMo particles in human bone marrow

Area of Science:

• Biomaterials Science
• Orthopedic Research
• Toxicology

Background:

• Cobalt-chromium-molybdenum (CoCrMo) alloy particles are implicated in chronic inflammation following arthroplasty.
• Limited data exists on the quantity, size, and elemental makeup of bone marrow particles, hindering relevant toxicological testing.

Purpose of the Study:

• To investigate metal particle exposure in human periprosthetic bone marrow from three arthroplasty implant types.
• To characterize particle number, size distribution, and elemental composition.
• To provide data for developing clinically relevant bone marrow models.

Main Methods:

• Spatially resolved and synchrotron-based nanoscopic X-ray fluorescence imaging.
• Analysis of periprosthetic bone marrow sections from eight patients.
• Quantification of particle concentrations per bone marrow volume and cell number.

Main Results:

• Lognormal particle size distribution, predominantly nanoscale, was observed.
• Particle concentrations reached up to 1 × 10¹¹ particles/ml bone marrow or 2 × 10⁴ particles/bone marrow cell.
• Cobalt content in CoCrMo particles correlated with particle size, suggesting dealloying and degradation.

Conclusions:

• This study provides the first quantitative data on metal particle concentrations and characteristics in human bone marrow.
• Findings support the hypothesis of cobalt release from larger arthroprosthetic particles via dealloying.
• The data is essential for future in vitro and in vivo studies on the toxic effects of CoCrMo particles.