Biological effects of metal degradation in hip arthroplasties

Abstract

Metals and metal alloys are the most used materials in orthopedic implants. The focus is on total hip arthroplasty (THA) that, though well tolerated, may be associated with local and remote adverse effects in the medium-long term. This review aims to summarize data on the biological consequences of the metal implant degradation that have been attributed predominantly to metal-on-metal (MoM) THA. Local responses to metals consist of a broad clinical spectrum ranging from small asymptomatic tissue lesions to severe destruction of bone and soft tissues, which are designated as metallosis, adverse reactions to metal debris (ARMD), aseptic lymphocytic vasculitis associated lesion (ALVAL), and pseudotumors. In addition, the dissemination of metal particles and ions throughout the body has been associated with systemic adverse effects, including organ toxicity, cancerogenesis, teratogenicity, and immunotoxicity. As proved by the multitude of studies in this field, metal degradation may increase safety issues associated with THA, especially with MoM hip systems. Data collection regarding local, systemic and long-term effects plays an essential role to better define any safety risks and to generate scientifically based recommendations.

Keywords:

• Total joint arthroplasty
• wear
• corrosion
• metal toxicity
• local adverse effects
• systemic adverse effects

Acknowledgements

The authors gratefully acknowledge the valuable comments offered by four reviewers who were selected by the Editor and anonymous to the authors. The authors also gratefully acknowledge Ms. Lucy Scioscia for assistance with English editing and revisions.

Declaration of interest

The employment affiliation is as shown on the cover page. The paper was prepared during the normal course of the author employment with grants from the Italian Ministry of Health “Ricerca Corrente” and “5 per mille 2015” for Health Research. D.G. planned the draft and initially wrote sections 1, 2, 4.1, 4.3, and 5.2. L.M.S. initially wrote sections 3.2, 4.4, 5.1 and 6. G.C. initially wrote sections 3.1 and 4.2 and prepared the illustrations. N.B. analyzed the clinical data and approved the final version of the manuscript. None of the authors have appeared in legal or regulatory proceedings with regard to the contents of this paper within the past 5 years. None of the authors have received compensation from manufacturers or marketers of implantable orthopedic devices. The authors all stand by the final interpretations of the papers and data and the conclusions drawn.