Effects of Twisting of the Graft in Anterior Cruciate Ligament Reconstruction

Abstract

In an in vitro study on six knees from cadavers, the effect of bone-patellar tendon-bone graft twist on anterior knee laxity was measured at different knee flexion angles. A motion and loading rig was used to prescribe the flexion angle, to restrain axial rotation, and to apply 100 N anterior force to the tibia. Roentgen stereophotogrammetric analysis was used to measure the relative anteroposterior position of the tibia and femur. The tibial bone block was cemented in a cylinder that allowed rotation in the bone tunnel. The anterior cruciate ligament was transected and reconstructed with neutral, 90 degrees, and 150 degrees internal twists and 90 degrees and 150 degrees external twists. External and internal graft twists in the reconstruction resulted in significant reductions of anterior laxity, however, at the cost of a more posterior position of the unloaded tibia relative to the femur (anteroposterior-error). The results are explained by the anterior relocation of the graft insertion by twisting the tibial bone block. The inclination angle of the graft in the anteroposterior direction flattens, which could improve the anterior laxity. A consequent side effect is the increase of posterior shift of the tibia relative to the femur.

Computer-assisted anatomically placed double-bundle ACL reconstruction: An in vitro experiment with different tension angles for the AM and the PL graft

“…This AP-error has previously been reported in other in vitro reconstruction studies [7,11,14,[26][27][28]. In agreement with those studies, the reconstructed knees showed the largest APerrors in extension.…”

Effects of Initial Graft Tension on the Tibiofemoral Compressive Forces and Joint Position after Anterior Cruciate Ligament Reconstruction

“…Graft twisting has been thought to increase the stiffness of the graft, but the relevance of graft twisting remains unclear and controversial. 10,23,40,50 Finally, we chose a standard 11-o'clock femoral position because it remains the standard in current practice for transtibial procedures. 31 It is possible that alternate graft orientations could influence our results.…”

In vivo kinematics of the ACL during weight‐bearing knee flexion

“…Previous studies have investigated the effects of graft twist on material properties, isometry, and anterior stability [6,7,17]. In these studies, the graft was twisted by as much as 180".…”