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

Anterior cruciate ligament reconstruction techniques are evolving with innovations like double-bundle (DB) grafts and computer assistance. The current DB techniques do not appear to make the clinical difference yet. Insight in various techniques may lead to better results. In this study, the anterior laxity of a DB reconstruction with an anteromedial (AM) graft fixated in 90° of flexion and a posterolateral (PL) graft fixated in 20° and computer-assisted anatomically placed femoral attachments was compared to normal values and single-bundle grafts. In 8 fresh-frozen human cadaveric knees, the anterior laxity was tested from 0° to 90° flexion, with a 100 Newton (N) anterior tibial load in joints with (1) intact ACL, (2) torn ACL, (3) single-bundle (SB) graft tensed with 15 N in 20°, (4) anatomic AM graft tensed with 15 N in 90°, (5) anatomic PL graft tensed with 15 N in 20°, and (6) anatomic DB graft (4 + 5).All reconstructions caused a posterior position of the tibia. Relative to the normal anterior laxity, the single-bundle techniques showed significantly increased laxities: The SB technique in 0° (+1.1 mm) and 15° (+1.7 mm); The AM reconstructions in 45° (+1.6 mm) and 90° (+1.5 mm); The PL reconstructions in all angles (from +1.4 to +2.3 mm), except in 0°. The anatomic DB technique showed no significantly increased laxities and restored normal laxity in all angles.