While primary ACL surgeries are generally successful with an 85-90% success rate, some grafts can re-tear. Common causes of failure include trauma, biology, and technical error, and patients will often experience instability following re-injury. Revision surgery may involve more than one knee ligament and are more technically challenging than primary ACL surgery. If another knee ligament, such as the medial collateral ligament or the posterior cruciate ligament, is injured, they will require reconstruction in addition to the ACL to prevent graft failure due to associated knee laxity.
Surgical techniques vary between primary and revision ACL reconstruction. There are multiple distinct factors that surgeons must take into account when planning revision ACL surgery. In ACL revision surgery, the choice of graft is important and depends on tunnel placement as well as the previous graft used. Patients have the choice of using their own tendon, and the tendon can be taken from a number of locations including the hamstring, quadriceps, the patellar tendon or the other knee.
The surgeon also has to adjust to conditions from the previous ACL reconstruction surgery. The surgeon may have to remove hardware from previous surgery and bone graft old tunnels to allow the drilling of new tunnels. Depending on the case, the surgery may need to be performed in two stages. Physical therapy following a revision can be more involved and take longer for full recovery compared to a primary surgery. In order to avoid re-injuring the same knee, it is recommended that patients do not resume sports as soon after the surgery as they might have after primary ACL reconstruction.
Ultimately, the decision to undergo revision surgery rests with the patient and depends on the lack of stability of the knee as well as the patient’s desired activity level. It is advised that patients considering revision surgery discuss their options with a specialist with experience in revision ACL surgery. The outcomes of revision ACL surgery are less predictable, but with good technique outcomes can be excellent.