Fixation strength of three different graft types used in posterior cruciate ligament reconstruction

Surgical reconstruction is generally recommended for PCL and associated ligament injuries. A variety of graft choices exist for PCL reconstruction surgery. This study evaluated the initial fixation strength of three grafts using in PCL reconstruction in a porcine model. Twenty fresh porcine knees were harvested and randomly assigned to four groups: bone-patellar tendon-bone graft, quadruple tendons graft, Achilles tendon graft, and normal PCL. After reconstruction the knee was tested on an MTS testing machine by translating the tibia posteriorly until failure at 30 degrees of flexion, neutral rotation, and anatomical vertical alignment. Biomechanical parameters including maximal failure load, stiffness, and failure modes, were analyzed and compared. In the maximal failure load, the four-strand tendon group was significantly greater than the other two grafts. However, it had greatest translation. There were no significant differences between the three grafts in stiffness. All three of these commonly used grafts had weaker initial fixation strength and stiffness than normal PCL. Graft failure occurred mainly at the tendon-bone junction and tendon-suture sites. The Patellar tendon group had significantly least translation during continuing loading.