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The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: A comparison of serum, synovial fluid, albumin, EDTA, and water
Author(s) -
Lewis A. C.,
Kilburn M. R.,
Heard P. J.,
Scott T. B.,
Hallam K. R.,
Allen G. C.,
Learmonth I. D.
Publication year - 2006
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20198
Subject(s) - phosphate , synovial fluid , calcium , bovine serum albumin , x ray photoelectron spectroscopy , chemistry , simulated body fluid , oxide , albumin , corrosion , nuclear chemistry , chromatography , chemical engineering , biochemistry , mineralogy , apatite , medicine , pathology , osteoarthritis , organic chemistry , alternative medicine , engineering
Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate‐buffered saline (PBS), EDTA in PBS, and water were studied using X‐ray Photoelectron Spectroscopy (XPS) and Time‐of‐Flight Secondary Ion Mass Spectroscopy (ToF‐SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy‐phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1587–1596, 2006