Is the Stryker Revolution mixing system fit for purpose? Reliability and a micro-CT assessment of cement porosity.

The Stryker Revolution (TM) is a new mixing system that employs a high vacuum and a motorised mixing spatula in an effort to reduce cement porosity. We have compared Revolution (TM) with Depuy Cemvac (R), in terms of system reliability and cement porosity. Standardised Simplex P (R) and SmartSet (R) HV cement samples were produced using both mixing systems and analysed using a micro-CT scanner. The overall porosity, number and volume of voids were measured. Void analysis was subdivided into macro-pores (>0.5 mm(3)) and micro-pores (0.0005-0.5 mm(3)). Both systems were easy to use and no breakages were encountered. There was no significant difference in overall porosity between Revolution (TM) and Cemvac (R). Revolution (TM) produced over a five-fold decrease in average macro-pore size with medium viscosity cement (p=0.02), but produced a greater number of micro-pores (p<0.01). SmartSet (R) HV specimens had a higher porosity compared to Simplex P (R). This study demonstrated that the Revolution (TM) system was reliable and reduced porosity at least as effectively as the established Cemvac (R) system. The Revolution (TM) produced a greater number of smaller pores and further testing is required to establish if this results in a significant mechanical benefit.