Cobalt-Chromium Metallosis with Normal ERG

Patients with a failed ceramic hip implant replaced by a cobalt-chromium implant may experience wear of the metallic implant from ceramic debris, resulting in elevations in serum cobalt and chromium. Within a year, patients may develop visual loss, sensory-neural hearing loss, hypothyroidism and cardiomyopathy. The visual loss has been assumed to be a toxic optic neuropathy. A previous case of cobalt/chromium toxicity suggests retinal involvement, with photopic ERG showing delayed and reduced amplitude and scotopic ERG showing reduced amplitude with an electronegative waveform.1 Here, we present a patient with early cobalt/chromium metallosis.