Abstract
Aims: To study clinicoradiological correlation with metal levels in patients with metal-on-metal hip resurfacings. Methods: Serum levels of Cobalt (Co) and Chromium (Cr) in 18 patients undergoing metal-on-metal resurfacing were measured preoperatively and at 6, 12, 24 and 36 months postoperatively. Implants were made of cast Co-Cr alloy. Cr analysis was by graphite furnace atomic absorption spectrometry (ETA-AAS) & Co analysis by inductively coupled plasma mass spectrometry (ICP-MS). Results: Patientsñ mean age: 51.6 years. Average preoperative levels of Cr and Co: 10.5 nmol/l & 7 nmol/l respectively. All patients showed increase in serum cobalt and chromium. Maximum Cr levels increased by 20 fold (range 5–106) and Co by 30 fold (range 3–91) after 12 months in 71% cases. In 69% cases, chromium levels were higher than cobalt levels. Downward trend was noted in 4 cases after 2 years postoperatively. Bilateral cases were similar to unilateral cases. Postoperative HHS was 77.2 (range 50.2–87.6). One dislocated hip had 171-fold increase of Cr and Co by 107 fold. No radiological abnormalities were noted. Conclusions: Increase in serum levels of both cobalt and chromium is due to ñself polishing phenomenonñ correlating with an increase of patientñs physical activity. This may stabilise or show a downward trend after 2 years. The patients with very high levels tended to be relatively young compared to others. Level of activity and age may determine amount of metal release from implanties.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
