Arthroprosthetic Cobaltism —



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Source & full article here: Arthroprosthetic Cobaltism —

Cobalt poisoning by hip replacement: Arthroprosthetic-Cobaltism

Stephen Tower, MD, University of Alaska, Alaska, USA

  • Cobalt, in excess, has the potential to block oxidative metabolism at the mitochondrial level.
  • The peripheral and central nervous systems, the heart, and the thyroid gland are variably compromised whether the means of cobalt exposure is iatrogenic (use of cobalt chloride as a hematemic), industrial (exhalation or ingestion of cobalt powders or ores), from the ingestion of cobalt laced beer (beer drinkers cardiomyopathy), or arthroprosthetic (wear of chrome-cobalt articular surfaces or corrosion and fretting of modular chrome-cobalt femoral necks and heads).
  • The toxicity of cobalt has been known since 1948.(1 2)
  • The first case report of arthroprosthetic-cobaltism was in Italian in 2001. The mechanism was wear or a revision chrome-cobalt femoral head by ceramic bits from the primary fractured ceramic component embedded in the revision plastic socket liner.
  • The degree of hypercobaltemia was unreported; symptoms of peripheral neuropathy were first noted 9 months after the first revision operation. Diagnosis was serendipitous.
  • A metal laden pericardial effusion was found on CT scan, prompting a radiograph of the asymptomatic hip revealing an aspherical femoral head. Resection arthroplasty was not performed until 16 months after the first revision operation, by then the patient’s pathology had progressed to severe motor and sensory neuropathy, pericardial tamponade, and hypothyroidism(.3)
  • Reports of 8 additional extreme cases of cobaltism from the ceramic-on-metal wear have followed. Blood cobalt levels in mcg/L ([BCo]) have ranged from 400 to 1000, latency to symptoms ranged from 3-48 months, and latency to diagnosis or revision surgery from 9 to 72 months.
  • All patients had neurologic pathology, most were hypothyroid, and all but three were noted to have cardiomyopathies. One patient died of heart failure, those patients followed > 6 months post second revision improved as their [BCo] declined.
  • The typical presentation of cobaltism was fatigue and anorexia, followed by numbness and weakness, hypothyroidism, deafness and blindness, and finally and sometimes fatally, heart failure or arrhythmias. Hypothyroidism was diagnosed in most cases before the diagnosis of cobaltism was made and some clinical improvement noted with onset of thyroid replacement therapy. None of the patients had notable sentinel hip symptoms before onset of overt systemic pathology.(4-11)

Additional Comments directly from Dr Tower:

As the new publication in OP notes we are now noting what appears to be cardiac and neurologic cobaltism in patients with MoP or even MoC hips if they employ taper junctions between CoCr and Ti components, in some patients even with single digit blood cobalt levels! It appears that if the Co is generated by Mechanically Assisted Crevice Corrosion that the material produced is more toxic mcg for mcg than that produce by articular surface wear. This is concerning because it is likely that about 90% of the hips done in the US over the past decade have likely employed a modular CoCr head. The Stryker Rejuvenate hip was certainly the canary in the cage for this mechanism of hypercobaltemia, pseudotumors, and potentially cobaltism.
We have redone about 15 Rejuvenate hips with hypercobaltemia ([BCo] > 1 mcg/L) for pseudotumors and several appear to have had cardiac and neurologic issue with [BCo] ranging from 4 to double digit. I also am seeing other commonly used hips that are out 5-10 years that are developing apparent taper corrosion problems with hypercobaltemia (range 1-4) pseudotumors, and in one case maybe a catastrophic cardio-vascular complication (aortic dissection). We now have 3 Alaskan patients that have developed lymphoma while implanted with a MoM hip (2 Duroms) and one Rejuvenate. All were hypercobaltemic. Latency from hip implantation to diagnosis was 3-7 years and in 2 case the diagnosis was incidental to revision surgery (one Durom) or the work-up suggested for patients with Rejuvenate hips (lymphadenopathy was noted on MS MRI).
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Cobaltemia and Cobaltism are common in Alaskans with failed Metal-metal Hips



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Cobaltemia and Cobaltism are common in Alaskans with failed Metal-metal Hips

by Dr Stephen Tower


Systemic cobalt poisoning from excessive wear of a hip implant was first reported in 2001. The male patient presented with profound peripheral neuropathy, a metal laden pericardial effusion, and immune thyroiditis in 1997. Notable elevations of cobalt and chromium were detected in the patient’s blood and urine. The patient had no symptoms at his prosthetic hip but the chrome-cobalt femoral head was out-ofround on radiographs. A Metal-on-Ceramic Wear Mechanism (MoCWM) explained the patient’s extreme cobaltemia. Ceramic bits from the broken primary femoral head embedded in the revision plastic socket liner and severely abraded the revision chrome-cobalt alloy femoral head. 1

Nine years later we reported the first two cases of ArthroProsthetic Cobaltism (APC) from a Metal-on- Metal Wear Mechanism (MoMWM). The articular surfaces of a Metal-on-Metal Hip Replacement (MoMHR) are wrought or forged of chrome-cobalt alloy. 2 Our patients’ ASR (DePuy) hips wore excessively resulting in notable cobaltemia. Both men developed disordered mood and cognition, audiovestibular dysfunction, rashes, and symptomatic cardiomyopathies. The more severely cobaltemic and involved patient developed retinopathy. His Blood Cobalt Level ([BCo]) peaked at 122BET (122 times the Biologic Exposure Threshold [BET] of 1 mcg/L) and 600 times the mean [BCo] of subjects without hip replacements. 2 3 4 5 The ASR hips were exchanged for Ceramic-on-Plastic (CoP) implants after 3.5 years because of progressive hip pain and noise, the periprosthetic tissues were stained by metal debris (metallosis) and wear of the explant of the index patient was 2 orders of magnitude above that predicted by the ASR’s designers. 6 Both men’s mood and cognition improved over months as their [BCo] declined. Their cardiomyopathies, rashes, audio-vestibular and optic impairments largely resolved over three years. 7 An author of this paper (ST) was the index case and he wrote that report. The second subject was the only patient that ST implanted with an ASR hip. The surgeon’s [BCo] during his ASR implantation and recovery, and the chronology of the development and resolution of his constitutional, dermatological, psychological, neurological, and cardiac cobaltism manifestations are depicted in Figure 1.7 His JBJS report was accompanied by a commentary commissioned by the Presidential Line of the American Academy of Orthopedic Surgeons (AAOS) that concluded: 3 8 “The report is unusual because of the rarity of the occurrence of metal-induced systemic complications in patients with total hip replacement and the fact that the author was one of the patients. As millions of patients worldwide have undergone total hip replacement, these cases represent rare events indeed. ”

The full 18 page original manuscript can be downloaded here Cobaltemia and Cobaltism Dr Stephen Tower Feb 2014

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Hell just froze over…



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Better late than never!

hell-freezes-overOrganized American orthopedics has just recognized that a blood cobalt level of 10 mcg/Liter  (same as 166 nmoles/Liter) and the development of symptoms consistent with cobaltism (poor sleep, mood changes, tinnitus, fatigue, weakness, tinnitus, deafness, visual changes, cardiomyopathy) is an indication have a metal-on-metal hip (stemmed or resurfacing) revised.

These guidelines are 4 years tardy but may improve the prospects of the million aware and unmonitored patients implanted with metal-on-metal hips.

Hopefully it will discourage surgeons from preforming any more hip resurfacings.

Click on this link to read the whole paper  Risk stratification Algorithm MoM 2014

The age of miracles is not yet past, it seems!

FaceBook comment from Stuart Cain – DePuy ASR victim – re Smith & Nephew BHR


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photos July Aug Sept 12 594Stuart Cain I was very interested to hear my surgeon say today that the Birmingham cases he is seeing are now out numbering the ASR and regardless of the fact that they are similar technology it has just taken 5 more years for the BHR cases to finally start coming to a head. I laughed at him and told him that there have been just as many BHR cases going bad, but for some reason we ASR ones have had all the attention. He did go on to state that regardless of the ‘attention’ he is having to do similar corrective surgeries (he did my 4th and 5th revisions of my ASR) of the BHR’s now and is starting to see more serious issues. I mentioned to him that maybe that might be because the BHR cases have been neglected by their surgeons for so long, he agreed. For the record my surgeon has never used any MOM technology.

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