Median 10-year whole blood metal ion levels and clinical outcome of ReCap-M2a-Magnum metal-on-metal total hip arthroplasty

• Published in: Acta orthopaedica 2022-04, Vol.93, p.444-450
• Main Authors: Pietiläinen, Sakari, Linnovaara, Axel, Venäläinen, Mikko S, Mäntymäki, Heikki, Laaksonen, Inari, Lankinen, Petteri, Mäkelä, Keijo T
• Format: Article
• Language: English
• Subjects: Arthroplasty; Arthroplasty, Replacement, Hip - adverse effects; Chromium; Cobalt; Hip Prosthesis - adverse effects; Humans; Ions; metal ion levels; metal-on-metal; Metal-on-Metal Joint Prostheses - adverse effects; Metals; Prosthesis Design; Prosthesis Failure; Reoperation
• ISSN: 1745-3674; 1745-3682
• DOI: 10.2340/17453674.2022.2510

We have previously reported that the whole blood (WB) chromium (Cr) and cobalt (Co) ion levels decrease in the short term after ReCap-M2a-Magnum large-diameter head (LDH) metal-on-metal (MoM) total hip arthroplasty (THA). This study reports long-term metal ion levels and clinical outcomes after ReCap-Magnum THA. ReCap-M2a-Magnum LDH THA was used in 1,450 patients in our hospital district from 2005 to 2012. Median follow-up time was 10 years. 991 patients had 2 or more metal ion measurements. The median measurement interval was 4 years. Individual metal ion change was assessed using logarithmic metal ion values in a random coefficient model. Kaplan-Meier survival estimates were calculated for revision surgery for any reason for revision, and separately for metal-related adverse events (metal ions above safe upper limit [SUL], revision due to ARMD, or pseudotumor). Geometric mean of Cr decreased from 1.8 ppb (geometric standard deviation [GSD] 1.8) to 1.0 ppb (GSD 2.8, p < 0.001). The Co levels decreased from 1.7 ppb (GSD 2.4) to 1.4 ppb (GSD 2.8, p < 0.001). The hip-specific survival was 85% for revision due to any reason at 14 years and the hip-specific survival for any metal-related adverse event was 69% at 14 years. WB Cr and Co levels continued to decrease in the long-term follow-up of ReCap-M2a-Magnum THA patients. The amount of metal-related adverse events was rather high, but revision surgery was seldom required. We suggest that after 10 years from the implantation a 5-year measurement interval may be sufficient for asymptomatic ReCap-M2a-Magnum patients.