Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft in anterior cruciate ligament reconstruction in a cadaver model

BACKGROUND: Compaction of the bone tunnel walls has been proposed to increase the fixation strength of soft tissue grafts fixed with an interference screw in anterior cruciate ligament reconstructions. HYPOTHESIS: Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft in comparison with conventional extraction drilling. STUDY DESIGN: Randomized experimental study. METHODS: Initial fixation strength of quadrupled hamstring tendon grafts fixed with bioabsorbable interference screws was assessed in 22 pairs of human cadaveric tibiae. Bone tunnels were drilled with either a compaction drill or a conventional extraction drill. Specimens underwent a cyclic-loading test and the surviving specimens were then loaded to failure in a single-cycle load-to-failure test. Trabecular bone mineral density at the site corresponding to the actual site of the tibial bone tunnel was determined by using peripheral quantitative computed tomography. RESULTS: During the cyclic-loading test, no significant stiffness or displacement differences were observed between the two drilling techniques. Three specimens failed in the compaction-drilling group, whereas there were no failures in the extraction-drilling group. In the subsequent single-cycle load-to-failure test, no significant differences between the two drilling techniques were found with regard to displacement at yield load, stiffness, or mode of failure. There was no significant difference in trabecular bone mineral density between the two groups. CONCLUSIONS: Compaction drilling does not increase the initial fixation strength of the hamstring tendon graft compared with conventional extraction drilling.