Long-Term Effects of Metal-on-Metal Cobalt-Chromium-Containing Prostheses Used in Total Knee Arthroplasty on Hearing and Tinnitus

Objectives: We aimed to determine the long-term effects of metal-on-metal (MoM) cobalt (Co)-chromium-containing prostheses used in total knee arthroplasty (TKA) on hearing and tinnitus. Methods: A total of 88 patients with the normal otoscopic examination and normal blood B12 levels, consisting of 44 patients who had been using MoM Co-chromium-containing total knee prosthesis for more than 5 years, and 44 non-implanted patients with similar demographic characteristics, were randomly selected and included in the study. Patients with previous ear surgery, chronic middle ear disease, or conductive hearing loss were excluded from the study. All participants were evaluated with pure-tone audiometry (PTA), distortion product otoacoustic emission (DPOAE), tinnitus handicap inventory (THI), and tinnitus reaction questionnaire (TRQ). Results: The mean age of the 88 patients was 67.22 +/- 10.4 years. The mean age of 44 patients who underwent TKA at least 5 years ago was 72.89 +/- 7.18 years, 75% of these patients had bilateral prostheses, and the mean prosthesis duration was 11.00 +/- 5.08 years (range 5-25). The two groups were compared statistically using PTA, DPOAE, THI, and TRQ scores. When the patient groups with and without prostheses were compared in terms of hearing and tinnitus, we did not find a significant difference between the two groups (p>0.05). Conclusion: In our study, we observed that the long-term use of MoM Co-chromium total knee prostheses did not have an ototoxic effect, contrary to what was believed. We also found that prolonged prosthesis duration or undergoing bilateral surgery did not worsen hearing and tinnitus.