title: Metal-on-metal hip prostheses and systemic health: a cross-sectional association study 8 years after implantation.
abstract: There is public concern over the long term systemic health effects of metal released from hip replacement prostheses that use large-diameter metal-on-metal bearings. However, to date there has been no systematic study to determine which organs may be at risk, or the magnitude of any effect. We undertook a detailed cross-sectional health screen at a mean of 8 years after surgery in 35 asymptomatic patients who had previously received a metal-on-metal hip resurfacing (MoMHR) versus 35 individually age and sex matched asymptomatic patients who had received a conventional hip replacement. Total body bone mineral density was 5% higher (mean difference 0.05 g/cm², P = 0.02) and bone turnover was 14% lower (TRAP 5b, mean difference -0.56IU/L, P = 0.006; osteocalcin, mean difference -3.08 ng/mL, P = 0.03) in the hip resurfacing versus conventional hip replacement group. Cardiac ejection fraction was 7% lower (mean absolute difference -5%, P = 0.04) and left ventricular end-diastolic diameter was 6% larger (mean difference 2.7 mm, P = 0.007) in the hip resurfacing group versus those patients who received a conventional hip replacement. The urinary fractional excretion of metal was low (cobalt 5%, chromium 1.5%) in patients with MoMHR, but creatinine clearance was normal. Diuretic prescription was associated with a 40% increase in the fractional excretion of chromium (mean difference 0.5%, P = 0.03). There was no evidence of difference in neuropsychological, renal tubular, hepatic or endocrine function between groups (P>0.05). Our findings of differences in bone and cardiac function between patient groups suggest that chronic exposure to low elevated metal concentrations in patients with well-functioning MoMHR prostheses may have systemic effects. Long-term epidemiological studies in patients with well-functioning metal on metal hip prostheses should include musculoskeletal and cardiac endpoints to quantitate the risk of clinical disease.
authors.affiliation: Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Prentice
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Clark
authors.forename: Nigel
authors.initials: N
authors.lastname: Hoggard
authors.forename: Allison C
authors.initials: AC
authors.lastname: Morton
authors.forename: Claire
authors.initials: C
authors.lastname: Tooth
authors.forename: Martyn N
authors.initials: MN
authors.lastname: Paley
authors.forename: Ian
authors.initials: I
authors.lastname: Stockley
authors.forename: Marios
authors.initials: M
authors.lastname: Hadjivassiliou
authors.forename: J Mark
authors.initials: JM
authors.lastname: Wilkinson
mesh_terms: D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000097:blood / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers