Biomechanical comparison of hamstring tendon fixation devices for anterior cruciate ligament reconstruction: Part 2. Four tibial devices.

We conducted a study to biomechanically compare 4 tibial hamstring tendon fixation devices commonly used in anterior cruciate ligament reconstruction. Quadrupled human semitendinosus-gracilis tendon grafts were fixed into porcine tibias using 4 separate fixation devices. For each device, 10 specimens were tested (1500-cycle loading test at 50-200 N). Specimens surviving the cyclic loading then underwent a single load-to-failure test. Failure mode, stiffness, ultimate load, and residual displacement were recorded. Eight of 10 Delta screw (Arthrex), 2 of 10 Retroscrew (Arthrex), 10 of 10 WasherLoc (Arthrotek), and 10 of 10 Intrafix (Depuy Mitek) devices completed the 1500-cycle loading test. Residual displacement was significantly (P < .001) lower for Intrafix (2.9 mm), WasherLoc (5.6 mm), and Delta (6.4 mm) than for Retroscrew (25.5 mm). Mean stiffness was significantly (P < .05) higher for Intrafix (129 N/mm) than for the other devices. Mean load to failure was highest for Intrafix (656 N), then WasherLoc (630 N), Delta (430 N), and Retroscrew (285 N). The Intrafix device demonstrated superior strength in the fixation of hamstring grafts in the tibia. WasherLoc was close behind.