When acl surgery failure?

Technical reasons: Less then optimal position of the graft in the femur and tibia can result in loss of motion, laxity and failure then again you tore the one you were born with and you can tear a graft. Seek guidance from an experienced knee surgeon.

Complex topic: Traumatic re-rupture is most common cause of acl graft failure. Failed surgical result can be due to: non-anatomic position of the graft or residual laxity-both can predispose to tear of meniscus+cartilage damage-or to associated injury that was missed in 1st surgery; stiffness; infection, poor rehab, other causes. See an ortho sports medicine specialist, consider getting 2nd opinion. Good luck!