Anteromedial versus central single-bundle graft position: which anatomic graft position to choose?

To compare the time-zero stability of an anatomic anteromedial (AM) single-bundle ACL reconstruction to an anatomic central (CTR) single-bundle ACL reconstruction. Twelve (6 paired) hip to knee cadaveric specimens were studied. Using custom ACL computer navigation software, a Lachman test and a previously validated, navigated mechanized pivot shift test were performed on 4 separate experimental groups in each specimen: (1) intact ACL, (2) ACL deficient with total medial and lateral meniscectomy, (3) following anatomic AM single-bundle ACL reconstruction, and (4) after anatomic CTR single-bundle ACL reconstruction. Maximum anterior tibial translation in each group was measured. Lachman: No significant difference was observed between the AM and CTR reconstructions (n.s.) or between reconstruction and the intact ACL (3.4 +/- A 1.7 mm) (n.s.). Pivot Shift: Both the AM and CTR ACL reconstructions significantly reduced anterior translation relative to the ACL/menisci-deficient condition (lateral compartment: 8.9 +/- A 3.8 mm and 6.75 +/- A 4.6 mm vs. 17.25 +/- A 3.5 mm, respectively; P < 0.001 and medial compartment: -3.0 +/- A 5.3 mm vs. -3.7 +/- A 5.7 mm vs. 6.2 +/- A 6.7 mm, P < 0.05). There was also a significant difference between the AM (P < 0.001) and CTR (P < 0.05) ACL reconstructions and the intact ACL (2.8 +/- A 4.4 mm) for lateral compartment translation. Further, no difference was found between lateral or medial compartment translations in the AM versus CTR reconstructions (n.s.). It has been shown that there was no difference in the time-zero biomechanical stability between an anatomic anteromedial and anatomic central single-bundle ACL reconstruction. Given the current debate on the best anatomic ACL reconstruction technique, anatomic socket position in either the anteromedial or central locations provides similar time-zero biomechanics.