Long-term study using of short stems with ceramic-on-metal bearing in hip replacement

BACKGROUND: Osteoarthritis is a disease that affects about 300 million people in the world. Surgery is indicated in cases where all other treatments have failed, in economic terms expenses are between 1 and 2.5% of the GDP of the most industrialized countries in the world. Hip prosthetic replacement surgery is the gold standard for patients affected by symptomatic osteoarthritis. The ceramic-on-metal (C-M) hybrid hard-on-hard bearing was initially launched on the market with the purpose of reducing adhesive and corrosion wear, loss of metal debris and ions and risk of fracture and squeaking. However, this bearing was withdrawn from the market, in the apprehension of local and systemic toxicity. The aim of this study is to evaluate the reliability and safety of ceramic-on-metal bearing at long term follow-up. METHODS: From 2 cohorts of patients suffering of hip osteoarthritis who underwent total hip arthroplasty using ceramic-on-metal bearing with two different short stems, 19 of the GROUP A and 25 of the GROUP B were suitable for this study. All compared clinically using the Harris Hip Score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analogue scale (VAS), 12-item Short Form Health Survey (SF12P/M), and radiographically. The two groups were compared in terms of metal ions blood levels (chromium and cobalt), and finally all the implanted prostheses were compared with a healthy control group. RESULTS: All the implanted stems were well osseointegrated at a mean follow-up of 114 months. Radiographical and clinical scores performed well. Chromium and cobalt ion analysis revealed values below the safety threshold except for 3. No revision occurred. CONCLUSIONS: Ceramic-on-metal bearing is safe and reliable at long term follow-up in association to short stems arthroplasty, if the implant is correctly positioned. Chromium and cobalt metal ions blood levels evaluation should be performed annually. KEY MESSAGES: • Metal ions evaluations is mandatory in patients with ceramic-on-metal bearing. • Ceramic-on-metal bearing is safe and reliable at long term follow-up, if the implant is correctly positioned.