What is a two-stage revision ACL reconstruction?
The anterior cruciate ligament (ACL) is one of the main ligaments inside the knee. It helps keep the shin bone (tibia) from sliding forwards and rotating under the thigh bone (femur). After an ACL reconstruction, the new ligament (graft) can stretch or tear again. A revision ACL reconstruction is an operation to replace the failed graft with a new one. In a two-stage revision, this is done in two separate operations, usually some months apart (PMID 32660548; PMID 36863622).
A two-stage revision is used when the bone tunnels from the first operation cannot be reused or worked around, most often because they have become too wide (tunnel widening) or were placed in a position that would clash with the new tunnels. When the tunnels can be reused or avoided, a one-stage revision is usually possible instead (PMID 36863622; PMID 39816950). Two stages may also be chosen when there is infection, marked stiffness or another problem in the knee, such as malalignment, that is best treated first (PMID 27045480; PMID 32660548).
The first stage is minimally invasive and is done with a knee arthroscopy (a camera inserted through small incisions). The old graft and any screws are removed, the tunnels are cleaned, and they are filled with bone graft. This may be your own bone, often taken from the rim of the pelvis (iliac crest), donor bone or a bone substitute (PMID 32660548; PMID 31116949). Once the bone graft has healed, the second stage is a revision ACL reconstruction: new tunnels are drilled in the correct position and a new graft is fixed in place, so that it sits in the same position and orientation as the natural ACL. The new graft is often taken from your own body, such as the patellar tendon, the quadriceps tendon or the hamstring tendons, and in some knees a lateral extra-articular tenodesis is added to help control rotation (PMID 36863622; PMID 42631105). In published studies, the time between the two operations ranged from about five months to just over a year (PMID 36863622).
A thorough clinical examination by a specialist and modern imaging helps confirm the diagnosis and plan treatment. Examination tests such as the pivot shift test and an MRI scan show that the graft has failed and whether the meniscus and cartilage are injured, and a CT scan shows the position and width of the old tunnels, which helps decide whether one or two stages are needed (PMID 42631105; PMID 39816950). Imaging is also used after the first stage to check that the bone graft has healed before the new ligament is placed (PMID 31116949).
What are the benefits of a two-stage revision ACL reconstruction?
A two-stage revision rebuilds the bone where the old tunnels were, so that the new tunnels can be placed in the correct position rather than being limited by the old ones (PMID 32042579; PMID 27045480). Staging also allows other problems, such as infection or stiffness, to be treated before the new ligament is placed (PMID 27045480).
It restores stability to the knee and improves knee function. In a review of 13 studies (355 patients), knee function and activity scores improved after two-stage revision (PMID 36863622). In a study that measured knee looseness with an instrument, knees were as stable after a two-stage revision as after a one-stage revision (PMID 40980494). In the Danish knee ligament registry (1,574 revision operations), knee stability improved significantly after both one-stage and two-stage revision, and about 3% of two-stage revisions needed a further revision within two years (PMID 38226705).
The new graft has a low failure rate. In a study of 176 revision operations, the risk of the new graft failing was lower after a two-stage revision than after a one-stage revision (PMID 39815325). In a review of bone grafting for two-stage revision, the new graft failed in 0–8% of patients, and failure rates tended to be lowest when the person's own bone was used to fill the tunnels (PMID 31116949).
What are the risks of a two-stage revision ACL reconstruction?
It needs two operations and two recoveries, so it takes longer and involves more surgery, time away from work and inconvenience than a one-stage revision (PMID 39816950; PMID 36863622). Between the two operations the knee does not have a working ACL, so sport and pivoting activities have to wait until after the second stage.
In the study of 176 revision operations, people who had a two-stage revision reported more pain at the front of the knee and lower knee function scores than those who had a one-stage revision (PMID 39815325). When bone is taken from the pelvis to fill the tunnels, it can cause pain and other problems at the harvest site (PMID 32042579).
Results of revision surgery are generally not as good as after a first ACL reconstruction. In a review of 21 studies (863 patients followed for at least two years), the new graft failed or the knee remained loose in 13.7% of people, three to four times the rate after a first reconstruction, and patient-reported knee scores were lower (PMID 22438002). Fewer people return to sport than after a first reconstruction (PMID 34096902; PMID 31286413); in a review of 3,814 patients having revision surgery, 48% returned to the same level of competition as before (PMID 41572915).
Damage to the meniscus and cartilage affects the long-term result. In a study of 1,234 people followed for six years after revision ACL reconstruction, those with meniscus or cartilage damage had poorer knee scores (PMID 36734487). Infection is rare: it occurred in 0.6% of 1,423 revision operations (PMID 33002248). Other risks are those of knee surgery in general, such as stiffness, blood clots, ongoing pain or swelling, and numbness or pain where the graft was taken.
Summary
A two-stage revision ACL reconstruction replaces a failed ACL graft in two operations: the first removes the old graft and fills the old tunnels with bone graft, and the second, some months later, places the new ligament. It is usually recommended when the old tunnels cannot be reused or avoided and the expected benefits for you outweigh the risks. You should discuss your symptoms, your scans and your goals, including plans for sport and work, with your knee surgeon so that you can consider the options, including whether one or two stages are needed, and the indications for surgery together.
General information only. The information on this page is general in nature and does not replace individual medical advice. All surgery carries risks, and results vary between patients. Please discuss your own circumstances with your treating practitioner.