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 20.56IU/L, P = 0.006; osteocalcin, mean difference 23.08 ng/mL, P = 0.03) in the hip resurfacing versus
conventional hip replacement group. Cardiac ejection fraction was 7% lower (mean absolute difference 25%, 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.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)