Biomechanical Study of Different Femoral Fixation Devices in the Reconstruction of the Medial Patellofemoral Ligament in Porcine Knees.

To evaluate different femoral fixation devices for medial patellofemoral ligament reconstruction and compare their effectiveness regarding fixation strength up to failure in porcine knees.  Thirty porcine knees were used, divided into three groups of 10 knees. The removed grafts were dissected from the extensor tendons of porcine feet. In each group, the graft was fixed to the femur with an interference screw, an anchor, or adductor tenodesis. The three methods were subjected to biomechanical tests using a universal Tensile testing machine at a speed of 20 mm/minute.  The highest average linear resistance under lateral traction occurred in group 1, "screw fixation" (185.45 ± 41.22 N), followed by group 2, "anchor fixation" (152.97 ± 49, 43 N); the lower average was observed in group 3, "tenodesis fixation" (76.69 ± 18.90 N). According to the fixed error margin (5%), there was a significant difference between groups (  < 0.001); in addition, multiple comparison tests (between group pairs) also showed significant differences. Variability was small, since the variance coefficient was lower than 33.3%.  Interference screws in bone tunnels and mountable anchors fixation with high resistance wire are strong enough for femoral fixation in porcine medial patellofemoral ligament reconstruction. Adductor tenodesis, however, was deemed fragile for such purpose.