Metal-on-metal hip prostheses: Correlation between debris in the synovial fluid and levels of cobalt and chromium ions in the bloodstream

Abstract

Purpose Hip prostheses with metal-on-metal (MoM) coupling can release cobalt-chromium particles and ions. The aim of this work is to verify the correlation between particles in the synovial fluid and circulating ions. Methods Forty patients were enrolled; particles from synovial fluid were analysed by SEM-EDX (Scanning Electron Microscopy-Energy Dispersion X-rays analysis) and levels of circulating Co and Cr were assayed by ICP-MS (inductively-coupled plasma mass spectrometry). Results In 16 cases we did not find any particles in the synovial fluid and the Co level in whole blood was 0.05-4.42 ppb; in seven with few particles the blood level was 2.2-15.6 ppb; in six cases with several particles the level was 5.0-54.3 ppb; finally, in 11 cases we isolated not only Co-Cr particles, but also Cr particles with low or absent Co and in these patients the circulating level of Co was 23.8-109.6 ppb. Co in serum and Cr level both whole blood and serum have shown a similar trend to Co; the correlation between all these values and the corresponding particles is statistically significant in all cases. Conclusion Co and Cr both in serum and whole blood represents a systemic representation of the particle release at local level and can therefore be used to confirm a diagnosis and monitor the wear process of MoM articular prostheses.

Repeated metal ion measurements in patients with high risk metal-on-metal hip replacement

“…It is clear that conventional follow-up methods (i.e., plain radiographs and clinical followup) are not sufficient to identify ARMeD in patients with MoM hips [4]. Hence metal ion assessment both from blood and synovial fluid, in addition to cross-sectional imaging, have been used to detect articulation related complications [4][5][6][7][8].…”

Management Guidelines for Metal-on-metal Hip Resurfacing Arthroplasty: A Strategy on Followup

“…Metal ion levels have been extensively used as a surrogate marker for patients with MoM bearings related wear 45. The population background level of Co in blood has been shown to be 0.5 μg/L, and the mean Co blood levels in patients with well functioning MoM hip implants ranges between 0.2 and 4 μg/L 46.…”

Surface replacement: A viable option for the right patient

“…This debris dissolves in the synovial fluid and disperses through the body via the bloodstream. Prior studies have shown good correlation of blood and synovial fluid metal levels [12,13]. Typically, the blood levels of cobalt and chromium, in a well-functioning SRA, are in the order of 2-3 parts per billion [14][15][16].…”