Failure mechanisms in CoCrMo modular femoral stems for revision total hip arthroplasty

Abstract

In this retrieval study, we reported the failure mechanisms of the CoCrMo-based hip implants. Systematic analyses on the clinically failed modular femoral stems from Revitan™ revision prostheses revealed a multistep fracture process. Multiple microcracks were first developed under the combined action of pitting corrosion and dynamic tensile stress on the lateral side of the CoCrMo connection taper. These microcracks then served as the initiation sites of further corrosion fatigue cracking leading to the final catastrophic failure. This crack initiation process has not been previously reported on retrieved CoCrMo components and our findings provide valuable information on the clinical performance of such implants, as well as the material selection and structural designs of future modular stems. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1525-1535, 2017.

Do Stem Taper Microgrooves Influence Taper Corrosion in Total Hip Arthroplasty? A Matched Cohort Retrieval Study

“…This allows for ion release into the joint space [25]. Wang et al [28] observed the transition between bulk CoCr material and oxide formation through material bands consisting of an oxide layer, transition layer and bulk material. It was thought that the introduction of micro-grooves could allow for crevice formation, altered contact stresses and localized corrosion [18].…”

Corrosion of Metallic Biomaterials: A Review

“…Industrial uses of stainless steels in saline environments also support possible susceptibility to SCC [2]. Wang et al [312] analysed the fracture of the CoCrMo connection taper in the Revitan™ revision modular femoral stem. It was concluded that the failure started with crack nucleation by SCC and propagated by corrosion fatigue.…”

Adverse reactions to metal on polyethylene implants: Highly destructive lesions related to elevated concentration of cobalt and chromium in synovial fluid

“…Although the etiology of the ALTRs was unknown, the high risk of ALTR in patients with hip resurfacing systems suggested that wear particles from the articulating surfaces would play a role in the development of the disease, and subsequently, it was thought that ALTRs could be prevented by switching the implant system from MoM to MoP. However, due to the evidence of ALTRs in modular hemiarthroplasty and in MoP THA, where the wear of metal bearing surfaces is minimal, it is now accepted that fretting corrosion at the modular interfaces of THAs may be the source of metals that lead to ALTRs …”

“…However, due to the evidence of ALTRs in modular hemiarthroplasty and in MoP THA, [10][11][12][13] where the wear of metal bearing surfaces is minimal, it is now accepted that fretting corrosion at the modular interfaces of THAs may be the source of metals that lead to ALTRs. 13,14 The concentration of Co and Cr in serum is considered a valid tool to screen the performance of MoM hip replacements. The Medicines & Healthcare Products Regulatory Agency (MHRA, UK) issued an alert in 2015 regarding the Birmingham MoM hip implants, recommending the monitoring of metal concentration in whole blood, establishing the maximum threshold for patients with MoM systems to be 7 ppb of Co or Cr as an indicator of potential development of soft tissue reaction.…”