title: Systemic cobalt toxicity from total hip arthroplasties: review of a rare condition Part 1 - history, mechanism, measurements, and pathophysiology.
abstract: Recently, the use of metal-on-metal articulations in total hip arthroplasty (THA) has led to an increase in adverse events owing to local soft-tissue reactions from metal ions and wear debris. While the majority of these implants perform well, it has been increasingly recognised that a small proportion of patients may develop complications secondary to systemic cobalt toxicity when these implants fail. However, distinguishing true toxicity from benign elevations in cobalt ion levels can be challenging. The purpose of this two part series is to review the use of cobalt alloys in THA and to highlight the following related topics of interest: mechanisms of cobalt ion release and their measurement, definitions of pathological cobalt ion levels, and the pathophysiology, risk factors and treatment of cobalt toxicity. Historically, these metal-on-metal arthroplasties are composed of a chromium-cobalt articulation. The release of cobalt is due to the mechanical and oxidative stresses placed on the prosthetic joint. It exerts its pathological effects through direct cellular toxicity. This manuscript will highlight the pathophysiology of cobalt toxicity in patients with metal-on-metal hip arthroplasties.
  
  
  CONCLUSIONS
  Patients with new or evolving hip symptoms with a prior history of THA warrant orthopaedic surgical evaluation. Increased awareness of the range of systemic symptoms associated with cobalt toxicity, coupled with prompt orthopaedic intervention, may forestall the development of further complications.
authors.affiliation: University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada.
authors.forename: A C
authors.initials: AC
authors.lastname: Cheung
authors.affiliation: Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, Maryland, USA.
authors.forename: S
authors.initials: S
authors.lastname: Banerjee
authors.affiliation: Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, Maryland, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Cherian
authors.affiliation: University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Wong
authors.affiliation: University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Butany
authors.affiliation: University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Gilbert
authors.affiliation: University of Toronto, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Overgaard
authors.affiliation: University of Toronto, 100 College Street Room 302, Toronto, Ontario, M5G 1L5, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Syed
authors.affiliation: University of Toronto, 100 College Street Room 302, Toronto, Ontario, M5G 1L5, Canada.
authors.forename: M G
authors.initials: MG
authors.lastname: Zywiel
authors.affiliation: Rush University, 1611 W. Harrison St., Suite 400, Chicago, IL60612, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Jacobs
authors.affiliation: Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, Maryland, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Mont
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D002273:Carcinogens; D003035:Cobalt / Q000009:adverse effects* / Q000493:pharmacokinetics; D006331:Heart Diseases / Q000209:etiology; D006402:Hematologic Diseases; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D007477:Ions / Q000009:adverse effects / Q000493:pharmacokinetics; D008107:Liver Diseases / Q000209:etiology; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects; D009369:Neoplasms / Q000209:etiology; D009422:Nervous System Diseases / Q000209:etiology; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013959:Thyroid Diseases / Q000209:etiology
chemical_list: D002273:Carcinogens; D007477:Ions; D003035:Cobalt
keywords: Hip; Metal-on-metal; cobalt; tociity