Abstract
The purpose of this paper is to investigate the relative contribution of each component in the ultimate strength and stiffness of the Evolgate (Citieffe), which is presently a widely used fixation device in DGST ACL reconstruction. The three components of the Evolgate were tested using fresh frozen animal tissue stored at −20° Celsius. Common extensor tendons were harvested from 20-month-old bovine forelimbs. Twenty-four tests were performed for each of the following configurations: six tests using Evolgate complete, six tests using screw alone, six tests using screw and washer and six tests using screw and coil. A randomised t-test was used; differences were considered significant when p< 0.05. The mean strength was: Evolgate complete 1314±194N; coil and screw 700±152N; screw alone 408±86N; and screw and washer 333±93N. There was a significant difference between fixation strength of Evolgate and the other devices, none between screw alone and screw and washer. The mean slippage of the Evolgate was significantly lower than the other devices. The mean stiffness of the Evolgate (269±14 N/mm) was significantly greater than the other devices. On the basis of the results of the present study, the coil appears to be the most important component of the Evolgate, resulting in a significant increase of the fixation strength of the screw. However, it is important to note that, as the washer alone does not improve the strength of the screw, if a washer is associated with a coil a further significant increase in strength and stiffness of the device is observed.
