The ototoxic potential of cobalt from metal-on-metal hip implants: a pilot study on the patient-reported auditory, vestibular, and general neurological outcome

Abstract

Objective

This study aimed to systematically investigate the ototoxic potential of cobalt in patients with a metal-on-metal (MoM) hip implant, using objective auditory and vestibular assessments and a questionnaire. The results of the objective evaluation were published previously, whereas the current study focused on the questionnaire outcome and its relationship to the blood cobalt level.

Design and study sample: Twenty patients (33–65 years) with a primary MoM hip implant and 20 non-implanted control subjects, matched for age, gender, and noise exposure, received a questionnaire to evaluate the presence of several hearing and balance symptoms (part 1) and general neurological issues (part 2).

Results

Concerning part 1, the proportion of auditory-related symptoms in general (p = 0.022) and tinnitus (p = 0.047) was significantly higher in the MoM patient group, whereas no group difference was found for hyperacusis, increased listening effort, and decreased speech understanding. Concerning part 2, no significant group differences were detected. Within the MoM patient group, the questionnaire outcome was not significantly different between the low-exposure and high-exposure subgroups according to the blood Co level.

Conclusions

In line with our previous study, these results potentially imply Co-induced impairment to the auditory system, despite the lack of a clear dose–response relationship.

Keywords:

• Metal-on-metal implant
• cobalt
• ototoxicity
• neurotoxicity

Acknowledgements

The authors thank Dr. Koen De Smet and Bart De Roest from the ANCA hip clinic (Ghent, Sint-Martens-Latem) for the assistance in the recruitment of patients with a metal-on-metal hip implant.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

L.L. has received funding from the Special Research Fund of Ghent University (BOF) [grant no. BOF15/DOC/330] and is currently receiving funding from the Research Foundation Flanders (FWO) [grant no. FWO/17/ASP/143], as a predoctoral research fellow.