title: How do metal ion levels change over time in hip resurfacing patients? A cohort study.
abstract: Metal-on-metal hip resurfacing (MOM-HR) is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. Nevertheless, concerns remain regarding wear and corrosion of the bearing surfaces and the resulting increase in metal ion levels. We evaluated three cohorts of patients with Birmingham hip resurfacing (BHR) at an average follow-up of 2, 5, and 9 years. We asked whether there would be differences in ion levels between the cohorts and inside the gender. Nineteen patients were prospectively analyzed. The correlation with clinical-radiographic data was also performed. Chromium, cobalt, nickel, and molybdenum concentrations were measured by atomic absorption spectrophotometry. Chromium and cobalt levels demonstrated a tendency to decrease over time. Such tendency was present only in females. An inverse correlation between chromium, implant size, and Harris hip score was present at short term; it disappeared over time together with the decreased ion levels. The prospective analysis showed that, although metal ion levels remained fairly constant within each patient, there was a relatively large variation between subjects, so mean data in this scenario must be interpreted with caution. The chronic high exposure should be carefully considered during implant selection, particularly in young subjects, and a stricter monitoring is mandatory.
authors.affiliation: Laboratory for Orthopaedic Pathophysiology and Regenerative Medicine, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Savarino
authors.affiliation: Department I of Orthopaedics and Traumatology, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136 Bologna, Italy ; Bologna University, Via Foscolo 7, 40123 Bologna, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Cadossi
authors.affiliation: Department I of Orthopaedics and Traumatology, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136 Bologna, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Chiarello
authors.affiliation: Laboratory for Orthopaedic Pathophysiology and Regenerative Medicine, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Fotia
authors.affiliation: Laboratory for Orthopaedic Pathophysiology and Regenerative Medicine, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136 Bologna, Italy.
authors.forename: Michelina
authors.initials: M
authors.lastname: Greco
authors.affiliation: Laboratory for Orthopaedic Pathophysiology and Regenerative Medicine, Rizzoli Orthopaedic Institute, Via di Barbiano 1/10, 40136 Bologna, Italy ; Bologna University, Via Foscolo 7, 40123 Bologna, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Baldini
authors.affiliation: Department I of Orthopaedics and Traumatology, Rizzoli Orthopaedic Institute, Via Pupilli 1, 40136 Bologna, Italy ; Bologna University, Via Foscolo 7, 40123 Bologna, Italy.
authors.forename: Sandro
authors.initials: S
authors.lastname: Giannini
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D002857:Chromium / Q000009:adverse effects / Q000627:therapeutic use; D003035:Cobalt / Q000009:adverse effects / Q000627:therapeutic use; D015331:Cohort Studies; D003343:Corrosion; D005260:Female; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008982:Molybdenum / Q000737:chemistry / Q000627:therapeutic use; D009532:Nickel / Q000737:chemistry / Q000627:therapeutic use; D011474:Prosthesis Design
chemical_list: D002857:Chromium; D003035:Cobalt; D009532:Nickel; D008982:Molybdenum