Abstract
ACL reconstruction is successful in restoring sagittal stability of the knee but has been less consistent in restoring rotational stability. Increasing coronal graft obliquity improves rotational constraint of the knee in cadaveric biomechanical models. The purpose of this study was to determine whether there is a correlation between coronal graft alignment and tibial rotation during straight line activities.
Seventy-four patients who had undergone ACL reconstruction using a transtibial technique were evaluated. They came from three distinct time periods during which the operating surgeon had deliberately changed the position of the femoral tunnel to progressively achieve a more oblique graft alignment in the coronal plane. Post-operative radiographs were analyzed for the coronal graft orientation and femoral and tibial tunnel positions. Tibial rotation was measured during level walking (n=74) and single-limb landing (n=42) tasks using a motion analysis system. Radiographic measurements of graft and tunnel orientation were correlated with rotational excursion of the knee recorded during these tasks. No correlations were found between knee rotational excursion and either the coronal tibial tunnel angle or the coronal graft angle during level walking. For the single-limb landing task, a significant negative correlation was observed between the coronal angle of the tibial tunnel and rotational excursion (r=−0.3, p=0.05) i.e. increasing tunnel obliquity was associated with decreasing rotational excursion. For the coronal angle of the ACL graft, the correlation was also negative, but was not significant (r=−0.24, p=0.12).
Increases in graft obliquity in the coronal plane were associated with reduced tibial rotational excursions during single limb landing. These findings support the notion that ACL graft orientation may play a role in rotational kinematics of the ACL reconstructed knee, particularly during higher impact activities.
