ACL (anterior cruciate ligament) reconstructions usually are performed with bone-patellar tendon-bone (BPTB) or hamstring (distal semimembranosus and gracilis) autografts. The Mri imaging appearance of an ACL reconstruction varies depending on the type of graft used and on the timing of imaging relative to graft placement. Mri examination is the best choice of imaging modality to study the complications of ACL reconstruction that usually are graft failure, graft impingement, and arthrofibrosis. The location of the femoral and tibial tunnels and graft position play a central role in the avoidance of impingement; the femoral tunnel should lie posterior to the intersection of Blumenstaat’s line (BL) with a line parallel to the posterior femoral cortex. This measure is well seen with conventional radiography but Mri imaging also allow to appreciate the integrity of the graft. I use all of the imaging modality in my daily practice but now my preference goes to dedicated systems; I think it’s very important to see what happens during knee flexion-extension to the reconstructed ACL.Dynamic evaluation of a normal reconstructed ACL. Sagittal dynamic Mri scan of the same patient.