Blind and deaf after total hip replacement? – Authors’ reply

J C Rompen and C C P M Verheyen state that symptomatic cobalt-chromium intoxication is extremely uncommon after total joint arthroplasty. There are indeed only four published Case Reports like ours, but this fact does not mean that these are the only existing cases worldwide. These are probably the ones in which systemic signs and symptoms have been correlated to cobalt release from a hip arthroplasty.

Rompen and Verheyen also state that studies show little evidence of significant metal wear when using metal-on-polyethylene articular components. However, in our case, as in the others published,

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metal-on-polyethylene components were used after the fracture of a ceramic head. This is the crucial point: the use of metal-on-polyethylene articular pairing should be contraindicated after ceramic head fracture because of the extraordinary severe metallosis seen.

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The explanation can be found in Paolo Gallinaro and Giorgio Piolatto’s letter: ceramic particles can be left behind and can act “like a grinding wheel” on the metal replacement.

Analysis of the removed prosthetic components revealed that both head and neck were worn; the polyethylene liner had a rough articulating surface with ceramic particles inside, left after the first arthroprosthesis revision, that had promoted metal wear. Histology of periprosthetic tissues revealed fibrous tissue with pronounced and widespread metallosis. A chemical analysis of articular washing liquid and tissue revealed that cobalt and chromium were the most represented elements (respectively 244 mg/L and 14·4 mg/g for cobalt; 547 mg/L and 16·9 mg/g for chromium). Our patient did not consent to a new implant, hence our decision to remove the prosthesis without replacement.

The aim of our report was not to cast a shadow on the safety of total hip replacement, but to throw light on the possible consequences of chronic exposure to very high concentrations of cobalt derived from revision surgery. Each of us should put on the glasses of science and reason to recognise important signs and symptoms even if they seem far from our own field of expertise. We did not become blind nor deaf when faced with this complex case which, under the guise of a neurological disorder, hid the toxicological solution to an orthopaedic problem.

We declare that we have no conflicts of interest.