Abstract

The ACCIS hip system has been marketed with a unique bearing surface which the manufacturers claim to reduce wear below the level of other MoM bearings and consequently less metal ion release. The cobalt-chrome-molybdenum alloy is heat treated to reduce the number and size of block carbides and the surface is modified with titanium-niobium-nitride to create a ceramic-like surface. We present our experience with ACCIS.

148 surgical procedures were carried out in 126 patients using the ACCIS hip resurfacing (77) or large head MOM total hip replacement(71). Patients were followed up with regular clinical and radiological assessment. In addition, metal ion levels were obtained. There have been 27 revision procedures carried out for a variety of indications with a current revision rate of 18%. Seven failures could not be attributed to the prosthesis itself, still leaving a failure rate of 13.5%. The mean survival time of these is 33 months, ranging from 1 to 72 months. 13 revisions were performed for pain and revision demonstrated poor cup integration. 7 were revised because of high ion levels but this was patient choice despite remaining asymptomatic.

Whilst the testing phases indicated benefits in wear characteristics, this is not apparent in our group. We have demonstrated an unacceptably high revision rate due to unknown causes and have ceased implanting the ACCIS.