Cadaveric experiments using knee testing machines have suggested that anatomical ACL reconstruction, replacing both antero-medial (AM) and postero-lateral (PL) bundles, restores knee rotation kinematics more effectively than does a single-bundle. The aim of this study was to measure intra-operatively the control of the translation and coupled rotations that occur with standard clinical laxity tests (anterior drawer, Lachman and pivot shift).

The knee kinematics of 10 patients were measured using a surgical navigation system and described in terms of tibial axial rotation and antero-posterior translation. In the ACL deficient knee, the average maximum tibial rotation during the pivot shift test was 29.0° and the mean maximum translation 17.0 mm. Reconstruction of the AM bundle (which behaves in a biomechanically similar way to a single-bundle reconstruction) reduced the rotational component to 16.4° (p< 0.0001) and translation to 6 mm (p = 0.0002). Addition of the PL bundle further reduced rotation to 12.6° (p = 0.0007) but had no significant effect on translation. Addition of the PL bundle also significantly reduced coupled tibial internal rotation during the Lachman and Anterior draw tests.

The pivot shift test simulates the instability suffered by patients with ACL deficiency and this study suggests that its rotational component is better restrained by anatomical, 2 bundle ACL reconstruction.