Abstract
Background
The CoCrMo large bearings had shown a high failure rate, because of metal ion and particle release. Alumina matrix composite (AMC) ball heads have shown to mitigate such phenomena. The aim of this study was to investigate the leaching properties of AMC clinically as well as experimentally.
Methods
Two patient groups were compared: a control group (n=15) without any implant (Controls) and 15 Patients with unilateral treatment with Biolox delta ceramic-on-ceramic (CoC). Whole-blood samples of Controls and Patients (after 3 and 12 months from treatment with CoC) were measured by means of trace element analysis using a HR-ICPMS. The leaching behaviour of BIOLOX delta was also analysed in-vitro: five Biolox delta heads and five CoCrMo heads were immersed in serum for seven days at 37°C. Aluminium, cobalt, chromium and strontium were detected based on HR-ICPMS.
Results
In Patients, most elements remained below the limit of detection (LoD), except for aluminium and strontium. The aluminium values of Controls were below the LoD (27.2μg/L). The values of Patients after three months show a median of 34.2μg/L and after 12 months 37.1μg/L (p=0,510). Strontium ranged from 39.7μg/L of Controls and 79.6μg/L and 70.7μg/L of Patients, after three and twelve months, respectively. This difference was not statistically significant (p=0,322). The leaching experiments showed high amounts of cobalt (177.3μg/L) and chromium (4.2μg/L) released by CoCrMo. Ceramic heads didn't show any significant release.
Conclusions
The current study revealed that there was no significant increase of any element in patients with CoC bearings. Metal heads released high values of cobalt in leaching test. As this release occurred even without any joint articulation, as shown in the experiments, surface corrosion seems to be a relevant mechanism in the ion release of metal bearings. A limitation of the study is that Controls differed from Patients within the clinical trial.
Level of evidence
III
