Clinical Manifestations in Ten Patients with Asymptomatic Metal-on-Metal Hip Arthroplasty with Very High Cobalt Levels

Abstract

Reports of adverse reactions to metal particle debris with metal-on-metal (MoM) hip arthroplasty have increased recently. Apart from the formation of pseudotumours and higher revision rates, another major cause for concern are the systemic effects of metal ions. Several effects of elevated systemic cobalt ions have been reported (e.g., myocardial and neurological effects, hypothyroidism). All 643 patients who underwent a stemmed large head MoM total hip replacement in our clinic were screened with repeated whole blood samples of metal ions (cobalt, chromium). We included ten asymptomatic unrevised patients with the highest cobalt concentrations, determined at a minimum of three years after implantation. These patients were subjected to an extensive neurological and cardiological screening protocol. In addition, blood samples were taken to assess renal and thyroid function. Ten patients with a cobalt level of 18-153 µg/L (mean 46.8 µg/L) were included. Nine patients were female, mean age was 65 years (range 56-75). The mean follow-up period was 4.2 years (range 3.0-6.1). Seven patients had bilateral stemmed MoM hip arthroplasty. No signs or symptoms of neurological dysfunction, cardiomyopathy, or renal or thyroid dysfunction could be identified or attributed to elevated cobalt levels. The clinical relevance of this study is that after short-term follow-up highly elevated blood cobalt levels do not cause systemic effects in our population. Hence in asymptomatic patients metal ions appear not to be a significant factor in the decision of when to revise a MoM large head total hip replacement.

A Systematic Review of Systemic Cobaltism After Wear or Corrosion of Chrome-Cobalt Hip Implants

“…Although the manuscript by Megaterio et al 15 did not include blood cobalt levels, we elected to include it because it was the first case report of arthroprosthetic cobaltism and the patient reportedly had significant increases in blood and urine cobalt levels. In total, we included 22 manuscripts, 14–16,23–41 one of which reported 3 patients, 37 three of which reported 2 patients, 32,38,39 and 2 occasions where descriptions of the same patient were reported twice. 29,34,40,41 This led to results for 25 unique patients.…”

Long – term survivorship and clinical results of the navigated withdrawn ASR ™

“…They therfore conclude that a large revision is not indicated in asymptomatic patients with highly elevated blood metal ions. 22 Christian et al demonstrated that the toxicological weight of evidence suggests that MoM hip implants are unlikely to be associated with an increased risk of systemic cancers, which is consistent with published and ongoing epidemiologic studies investigating the relationship between elevated Co and Cr serum levels and increase in systemic cancers. 23 Paustenbach et al, who examined the connection between Co serum concentrations and adverse biological effects, concluded that only under very unusual circumstances biologically important systemic effects might occur in MoM hip implant patients with Co serum concentrations of less than 300 ppb.…”

Metal Ion Release after Hip and Knee Arthroplasty – Causes, Biological Effects and Diagnostics

“…Chen et al [38] were able to show discrete changes in some immune markers, but no impairment of liver or kidney function, after a rather short follow-up of two years following MoM large head hip arthroplasty. Likewise, the study of Van Lingen et al [39] did not find any organ damage in a group of 10 patients with significantly elevated cobalt levels (mean 46.8 µg/l, 18-153 µg/l) from a total cohort 643 of patients 4 years after MoM large-head hip arthroplasty. In summary, while isolated cases of problem implants and, above all, metal head use in revision surgery for previous ceramic fracture run the risk of cobalt-related organ damage, this will not impact most patientsespecially those with clinically well-functioning MoM implants.…”