Interference screw fixation of soft tissue grafts in anterior cruciate ligament reconstruction: part 1: effect of tunnel compaction by serial dilators versus extraction drilling on the initial fixation strength.

Abstract

Compaction of the bone-tunnel walls by serial dilation is believed to enhance the interference screw fixation strength of the soft tissue grafts in anterior cruciate ligament (ACL) reconstruction. Serial dilation enhances the fixation strength of soft tissue grafts in ACL reconstruction over extraction drilling. Randomized experimental study. Initial fixation strength of the doubled anterior tibialis tendon grafts (fixed with a bioabsorbable interference screw) was assessed in 21 pairs of human cadaver tibiae with either serially dilated or extraction-drilled bone tunnels. The specimens were subjected to a cyclic-loading test, and those surviving were then tested using the single-cycle load-to-failure test. During the cyclic-loading test, there were 3 fixation failures in the serially dilated and 6 failures in the extraction-drilled specimens but no significant stiffness or displacement differences between the groups. In the subsequent load-to-failure test, the average yield loads were 473 +/- 110 N and 480 +/- 115 N for the 2 groups respectively (P =.97) and no difference with regard to stiffness or mode of failure. Serial dilation does not increase the strength of interference fixation of soft tissue grafts in ACL reconstruction over extraction drilling. The results of this experiment do not support the use of serial dilators in ACL reconstruction.