The cardiac manifestations secondary to systemic cobalt toxicity in this patient represent a frightening consequence of MOM prosthetic wear. The effects of cobalt toxicity on cardiac tissues were first described in a series of alcoholic patients from Manchester in 1900;7 however, it was not until 1967, in a series of patients in Quebec, that cobalt was found to be the inciting factor. In the modern era, hip arthroplasty techniques resulting in excessive cobalt and chromium wear have demonstrated the same findings of myocyte hypertrophy, interstitial fibrosis, and scattered myofibers containing large cytoplasmic inclusions.8,9 The patient presented here has pathologic findings consistent with previous cases of cobalt cardiomyopathy; however, in the other cases of cardiomyopathy due to MOM total hip components, the patients’ cardiac conditions improved after the prostheses were revised and the cobalt levels began to diminish.5,6In our case, the patient has sustained permanent damage to his myocardium and a progressive decline in his cardiac status, which is a deviation from reported cases as of 2014.
While there is no guideline to unequivocally diagnose cobalt cardiomyopathy, the constellation of findings, including pathologic, biologic, blood levels, imaging, and surgical, all uniformly indicate a unifying diagnosis. The lack of improvement after prosthetic device removal supports a diagnosis of permanent myocardial damage, which is consistent with cardiomyopathy of advanced toxic etiology.
Conclusion
This case presents a patient with bilateral MOM THAs, acetabular cup inclinations of greater than 55º, renal impairment, and cobalt levels greater than 60 ppb, with occult cardiac failure leading to LVAD implantation as a prelude to cardiac transplantation in order to avoid certain death. These factors have been shown, in prior case reports, to be associated with cardiac damage that may be reversible.6 However; it is important for orthopedic surgeons to recognize that certain hip prostheses can be associated or lead to irreversible cardiac damage.