“Doctors put drugs of which they know little into bodies of which they know less for diseases of which they know nothing at all.”  - Voltaire, 1715

 

There is little doubt that medical therapeutics and the knowledge of human physiology and pathology have progressed since 1715 but it is likely that there is no better way for a physician to understand an ailment and the risks associated with its remedy than to experience both first hand.

 

When I elected to have my hip replaced in 2006, I had twenty years of experience scrubbing in on that operation. I also had contributed to improving hip implant design and to optimizing the treatment of femur fractures that can complicate hip or knee replacement. (1,2)

 

I had followed the same advice that I give my younger patients about the timing of joint replacement. For a decade I had been modifying my fitness activities until cycling was the only means I had to maintain my fitness. Once that activity became limited to a 6-mile commute home from the hospital, I signed up for the operation that I knew best and most enjoyed performing.

 

My rationale for selecting my particular implant seemed sound, particularly in light of my research on the shortcomings of thin plastic hip socket liners. (2) Despite an academic interest in hip implant materials and design and 14 years of experience replacing hips in private practice, I was unaware that my particular implant, like most hip implants available in the United States, had only a cursory pre-market review by the FDA. My accelerated return to endurance cycling competition reinforced my impression that I had made an optimal selection. My own experience led me to choose an implant with flawed technology into some (fortunately only 6) of my younger, more active patients.

 

Over 42 months, my replaced hip became painful to the point that I was again limited to a 6-mile bike ride. More concerning, I had also developed sleep disturbance, mood instability, imbalance, tinnitus (ringing in the ears), retinopathy, and stiffening of the heart (diastolic cardiomyopathy).

 

When my hip was finally revised, a crankcase of metallic sludge was found which had irreparably damaged the ligaments about the hip that provide stability. This deficiency resulted in 10 dislocations of the revised hip. Thankfully, the pain at the hip largely resolved, as did my cardiomyopathy, disordered mood sleep disturbance, hearing issues, imbalance, and vision issues.

 

Before the revision operation, the cobalt concentration in my blood was found to be 120 times that which is thought to be safe for cobalt-exposed workers and my cerebrospinal fluid (CSF) cobalt level became the third highest reported in the literature at that time.

 

The publication of my experience, combined with that of one of my patients, was the first time that systemic cobalt poisoning/cobaltism was noted as a potential complication of metal-on-metal hip replacement. (3) This was initially felt to be an extraordinarily rare occurrence. (4) Over time, additional cases were reported and cobaltism became noted to be one of the complications of metal-on-metal hip replacement, which led to its commercial demise. Additionally, it led to the concept that patients implanted with metal-on-metal hips ought to be monitored for systemic cobalt poisoning/cobaltism in addition to being screened for damage to the tissues around the hip implant. (5)

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Of all of the metal-on-metal hips implanted, only 93,000 were formally recalled, leading to concern that numerous patients might be at risk for developing cobaltism/systemic cobalt poisoning.