Review of evolution of tunnel position in anterior cruciate ligament reconstruction

Table 2 Biomechanics summary

Ref.	Study type	Femoral tunnelpositioning	Anatomic or isometricgraft placement	Tibial tunnelpositioning	Results
Loh et al[43]	Controlled laboratory study	Reconstructed bone-patella tendon-bone graft at the 10 and 11-o’clock position	-	-	Both the tunnel positions were equally effective under an anterior tibial load, the 10-o’clock position more effectively resists rotatory loads when compared to the 11-o’clock position
Scopp et al[45]	Controlled laboratory study	Reconstructed bone-patella tendon-bone graft at standard or oblique tunnel position	-	-	The group with the standard 30° from vertical reconstruction had significantly more laxity in internal rotation. The oblique 60° femoral tunnel more closely restored normal knee kinematics
Markolf et al[44]	Controlled laboratory study	Compared the ACL graft placed at the 11-o’clock and 9:30- to 10-o’clock femoral tunnel positions during a simulated pivot shift event	-	-	There were no significant differences in tibial rotations or tibial plateau displacements during the pivot shift between standard and oblique femoral tunnels
Musahl et al[30]	Controlled laboratory study	-	Tested cadaveric knees in response to a 134 N anterior load and a combined 10 Nm valgus and 5 Nm internal rotation load	-	A femoral tunnel placed inside the anatomical footprint of the ACL results in knee kinematics closer to the intact knee than does a tunnel position located for best graft isometry
Driscoll et al[46]	Controlled laboratory study	-	Compared femoral tunnels that were reamed through the anteromedial portal and centred alternatively in either the AM portions of the femoral footprint or the centre of the femoral footprint		Femoral tunnel positioned in the true anatomic centre of the femoral origin of the ACL may improve rotatory stability without sacrificing anterior stability
Abebe et al[47]	Controlled laboratory study	-	Compared femoral tunnels that was placed near the anterior and proximal border of the ACL and another near the centre of the ACL footprint	-	Grafts placed anteroproximally on the femur were in a more vertical orientation and therefore less likely to provide sufficient restrain. Normal orientation of the graft was better achieved with anatomical placement of the graft ultimately resulting in a more stable knee
Bedi et al[50]	Controlled laboratory study	-	-	Evaluated the effect of 3 tibial tunnel positions on restoration of knee kinematics after ACL reconstruction: over the top (non-anatomic positioning), anterior footprint and posterior footprint with a standard central femoral tunnel position at the femoral ACL footprint	Anterior positing of the tibial tunnel either in the over the top position or at the anterior foot print produces favourable kinematics than posterior positioning of the tibial tunnel. However, there is a risk of causing secondary notch impingement leading to graft attrition and failure

ACL: Anterior cruciate ligament; AM: Anteromedial.