Abstract
Introduction
The articulating surfaces of a new metal-on-metal (MoM) hip prosthesis system were modified with the ceramic Titanium-Niobium-Nitride (TiNbN) by Physical Vapor Deposition (PVD). The purpose of the study was to investigate whether the elevation of the ion levels of chromium and cobalt, normally seen in the blood of patients after MoM hip arthroplasty, can be prevented by ceramic engineering of the articulating metal surfaces.
Materials and methods
the ACCIS components (manufactured by Implantcast GmbH, Buxtehude, Germany from casted hi-carbon Co-Cr-Mo alloy) are heat treated, polished and micro-surface finished. Then TiNbN ceramic is integrated into the metal surfaces by PVD.
200 ACCIS resurfacing hip prostheses were implanted in three centres: Morriston Hospital, Swansea and Neville Hall Hospital, Abergavenny in the UK and Arthro Clinic, Hamburg, Germany. Blood samples of 60 randomly selected patients were analysed before surgery and at intervals of 3, 6, 12 and 24 months after surgery. Independent trace metal measurements were performed at the Universitätsklinikum Carl Gustav Carus Dresden, Germany.
Results
the median chromium concentrations after 2 years were 0.94 (0.25-3.6) and the median cobalt concentrations after 2 years were 1.04 (0.07-2.36) μ gr/L. The average chromium concentration after 2 years was 1.073 and the average cobalt concentration after 2 years was 1.095 μ gr/L. None of the patients at any moment after operation showed an obvious increase of Cr and Co ions in the blood. Metal ion levels above the normal limits as described in the “Hand book for environmental medicine” were not seen (1).
Conclusion
surface engineering of metal articulating surfaces effectively minimises corrosion and metal ion release.
