Persistence of the Mini Pivot Shift after Anatomically Placed Anterior Cruciate Ligament Reconstruction

We hypothesized that traces of pivot-shift instability (a minipivot) would persist after anterior cruciate ligament reconstruction in some knees despite objective restoration of anteroposterior laxity to normal. We tested intact cadaver knees after anterior cruciate ligament transection and then after anatomically placed single-bundle anterior cruciate ligament reconstructions. We measured the rotational laxities and pivot-shift kinematics over a range of graft tensions. Increasing graft tension decreased anteroposterior laxity; anteroposterior laxity was greater than normal at 0 and 10 N tensions but not different than normal at 20 to 60 N tensions. Anterior cruciate ligament deficiency had little effect on rotation laxity, and reconstruction had little effect on rotational laxity, which was not reduced by increasing graft tension. During the pivot-shift test, increasing graft tension reduced the anteroposterior subluxation-reduction events, but tibial rotational was not restored to normal. More sophisticated reconstruction methods may be required to control rotation. Objective restoration of anteroposterior laxity to normal does not necessarily return knee kinematics, especially rotational behavior, to normal.