Biomechanical evaluation of posterolateral corner reconstruction with suture augmentation in a posterolateral corner and posterior cruciate ligament deficient knee model

Background: Posterolateral corner injuries are relatively uncommon but difficult to successfully treat. This study evaluates the biomechanical stability of a novel reconstruction technique utilizing suture augmentation and compare it to the traditional LaPrade technique. Methods: Eight matched pairs of all-male cadaveric knees were divided into two groups: (1) Posterolateral corner reconstruction and (2) reconstruction with suture augmentation. Each knee was tested in 3 states sequentially in isolation: (1) intact, (2) deficient posterolateral corner+Posterior cruciate ligament, and (3) after posterolateral corner reconstruction or reconstruction with suture augmentation. Each knee was repeatedly tested by applying a 134 N posterior load, 10 Nm varus moment, and 5 Nm of external rotary moment at 0, 30, 60, and 90 degrees of flexion while rotation and displacement of the tibia relative to the femur were recorded. Findings: Both reconstruction techniques restored posterior tibial displacement to levels that were less than the deficient state (p < 0.01) but greater than intact knees (p < 0.001). Suture augmentation recorded less posterior displacement compared to reconstruction alone (30o =-1.2 mm, 60o =-1.0 mm, 90o =-0.6, p < 0.01). Both techniques restored varus stability to intact levels at all flexion angles except at 90o. Suture augmentation allowed external rotation closer to intact values compared to reconstruction alone at all angles (0o =- 3.7o, 30o =- 4.8o, 60o =- 6.0o, 90o =- 5.3 o)." Interpretation: At time zero, reconstruction with suture augmentation decreases knee external rotation compared to reconstruction alone. Both reconstruction techniques restored restraint to varus rotation back to intact levels at most flexion angles, while neither restored posterior translation back to intact levels.