Table III.

A summary of published research into cardiovascular complications of metal-on-metal hip arthroplasties.

Reference	Study design	Study group	Control group	Study group blood cobalt, µg/l	Findings
Prentice et al65	Cross-section associational study	Aymptomatic patients with MoM hip resurfacings	Age- and sex-matched patients with non-MoM hip arthroplasties	Whole blood cobalt 1.75 µg/l compared to 0.38 µg/l in control group	Cardiac ejection fraction reduced and end diastolic volume increased in MoM group
Lodge et al69	Single centre, non-randomized, observational study	Patients with MoM hip arthroplasties in 3 groups, separated by cobalt levels	Age-matched controls with non-MoM hip arthroplasties	Plasma cobalt in 3 study groups 14.6 µg/l, 7.8 µg/l, and 1.3 µg/l compared to 0.6 µg/l in control group	Increasing cobalt values associated with increased heart volume but not with cardiac dysfunction and no clinical difference between groups was demonstrated
Berber et al70	Prospective, single centre, blinded trial	MoM bearing with elevated blood cobalt ions	MoM bearing with low blood cobalt ions and CoC bearing	Whole blood cobalt 30 µg/l and 2.47 µg/l in respective MoM groups compared to 0.17 µg/l in control group	No relationship between cobalt levels and ejection fraction. No differences between groups in the left atrial or ventricle size, B-type natriuretic peptide level, or troponin level, and all values were within normal ranges
van Lingen et al71	Longitudinal cohort study	10 asymptomatic MoM patients with highest cobalt levels out of a population of 643 MoM patients	None	Whole blood cobalt 18 to 153 µg/l (mean 46.8 µg/l)	No signs or symptoms of cardiomyopathy could be identified
Gillam et al67	Observational cohort study from Australian Government Department of Veteran’s Affairs health claims database	63 men with an ASR XL THA	1,502 men with MoP THA, 199 men with other MoM THAs, 2,044 women with MoP, 58 women with ASR XL THA, and 153 women with other MoM THAs	Not recorded	Men with an ASR XL THA had a statistically significant higher rate of hospitalization for heart failure than men with a MoP THA. This higher rate of heart failure was not demonstrated in women or in men with other types of MoM implants
Lassalle et al68	Cohort study in the French National Health Insurance Databases	11,298 patients with MoM hips	93,581 patients with MoP, 58,095 patients with CoP, 92,376 patients with CoC	Not recorded	Small increase in heart complications in metal bearing surfaces compared to non-metal surfaces was identified after controlling for confounding factors, most pronounced in MoM vs CoC in women and men over 75 years of age
Goodnough et al72	Analysis of the Standard Analytics Files database in the USA	29,483 patients with MoM hips	24,175 patients with non-MoM hips	Not recorded	At 5 years there was no difference in cardiac complications such as cardiac failure, arrhythmia, acute myocardial infarction, or cardiomyopathy
Sabah et al73	Linkage study between the National Joint Registry, Hospital Episodes Statistics and records of the Office for National Statistics on death	53,529 patients with MoM hips	482,247 patients with non-MoM hips	Not recorded	At 7 years the risk of cardiac failure was lower in the MoM cohort compared with the non-MoM cohort. When the groups were matched their risk of cardiac failure was similar.
Juneau et al66	Cross-section study using cardiac magnetic resonance	20 MoM resurfacing patients, 10 bilateral, 10 unilateral	10 case-matched non-MoM total hip arthroplasty patients	Mean serum cobalt 1.3 µg/l in study group compared to 0.18 µg/l in control group	None of the MoM patients showed clinically significant cardiac functional abnormality. The MoM patients had larger end diastolic volumes. There was a small decrease in T2 time in the MoM patients. Higher metal ion levels were associated with larger LV volumes and with shorter T2 time.

CoC, ceramic-on-ceramic; CoP, ceramic-on-polyethylene; LV, left ventricular; MoM, metal-on-metal; MoP, metal-on-polyethylene; THA, total hip arthroplasty.