The majority of ACL reconstruction surgeries will result in a positive outcome, with an extremely low failure rate. However, failed ACL surgery does occur, as a result of new trauma, improper surgical techniques, such as non-anatomical graft placement, improper or incomplete rehabilitation, or in rare cases, as a result of failure of biological healing.
In cases of ACL revision, your physician must first attempt to determine the cause of failure, in order and to plan ACL revision for failed ACL surgery, to lower the risk of second failure.
A primary cause of failure is a poorly positioned ACL graft. In patients where the graft is completely misplaced, it is often possible to ignore the previous graft sockets, and simply place an anatomic graft. However, if the position is wrong, but overlaps the proper position, then the old sockets must be filled, allowing anatomic sockets to be created. Frequently, old hardware, such as screws or buttons, requires removal. In cases of overlap of the proper position, with gross socket widening, or in cases of multiple failed surgeries, your physician sometimes recommends a two-stage revision. However, whenever possible, patients prefer a single procedure, and your physician may perform one-stage revision if at all possible.
Patients with severe tunnel widening, multiple failed surgeries, or poorly placed tunnels, will have a two-stage revision. Stage one is the removal of the old hardware, and bone grafting the previous bone socket defects. After 3-6 months, the tunnels are filled in, and the knee reacts and feels like a normal knee, with no old ACL sockets. Following this, the stage-two revision is more like a primary surgery. An advantage of two-stage revision, when required, is that the outcomes come the closest to primary ACL reconstruction, as published in research, as compared to single-stage revision. Most patients are candidates for single stage revision.
Finally, a frequently unrecognized cause of ACL graft failure is associated insufficiency of other knee ligaments. When this is the case, your physician may be required to reconstruct the medial or lateral collateral ligaments, or the posterior cruciate ligament, at the same time of an ACL revision, with a goal as avoiding a second graft failure.