A biomechanical comparison of tibial back side fixation between suspensory and expansion mechanisms in trans-tibial posterior cruciate ligament reconstruction

Abstract Soft tissue grafts have attracted increasing attention in anterior cruciate ligament (ACL) reconstruction and offer a number of advantages Therefore, it can also be attractive for trans-tibial PCL reconstruction, if four-strand hamstring or two-strand tibialis grafts could be converted for this use. We intended to investigate the biomechanical properties of fixation devices that are frequently used for the soft tissue graft in the trans-tibial PCL reconstruction.Thirty-six fresh adult porcine knees were used in this study. Porcine digital extensor tendons were used as two-stranded soft tissue grafts. The tibial side of the PCL was fixed using a bio-TransFix of suspensory mechanism (TransFix system®: Arthrex, Naples, FL, USA) device (group I) or a RIGIDFIX of expansion mechanism (RIGIDFIX system®: Mitek, Johnson & Johnson, USA) device (group II). We performed biomechanical testing to identify maximum failure load, stiffness, and displacement for both devices.Maximum mean failure loads in groups I and II were 907.3±142.2 and 701.9±101.5N, respectively ( p =0.03). Stiffness was 65.6±16.8 and 63.1±15.1N/mm, respectively ( p =0.85). Mean displacements were 23.9±6.0 and 19.8±7.9mm, respectively ( p =0.37).Suspensory and expansion mechanisms used for tibial back side fixation in the trans-tibial PCL reconstruction using soft tissue grafts showed acceptable biomechanical properties and could be a good choice in case of short multi-stranded soft tissue graft.