This study investigated a series of Kinemax knee replacements where the survival rate was only 75% at nine years, compared with previously recorded rates of 96% over ten years and tried to ascertain the reason for the significantly lower survival rate.
The authors discovered that on revision ‘the most striking feature was polyethylene wear’ on the implant and therefore undertook to have the removed implants independently anaylsed for abnormalities.
The findings of scanning the implants using electron microscopy were type 2 fusion defects in the polyethylene, indicating incomplete boundary fusion. Therefore, the authors ‘consider that the failure of the Kinemax implants in our cohort was due to material failure of the UHMWPE, probably at the time of manufacture, exacerbated by post-manufacturing oxidation’.
Source: The Journal of Bone and Joint Surgery