Reviewed by Dr Vishal Pai
Revision ACL surgery reconstructs the anterior cruciate ligament (ACL) again after a previous ACL reconstruction has failed. This page covers why grafts fail, how a revision is planned (sometimes in two stages), what recovery looks like and the results you can expect.
At a Glance
- Revision ACL surgery replaces a graft that has torn or stretched, and aims to correct the reasons the first reconstruction failed.
- Not every failed graft needs surgery. If your knee stays stable and you avoid high-demand activities, you may manage without it.
- Some people need two operations: bone grafting of the old tunnels first, then the new reconstruction 4–6 months later.
- Recovery is generally slower than after a first ACL reconstruction.
- Most people return to some sport, but only about half get back to their previous level.
What is revision ACL surgery?
Revision ACL surgery is performed when a previous reconstruction has failed and the graft has re-torn. The goal is to reconstruct the ligament while addressing the factors that led to the initial failure.
Revision surgery is technically more complex than a first (primary) ACL reconstruction. The procedure is tailored to each person, with a focus on identifying and correcting the causes of graft failure.
Why do ACL reconstructions fail?
ACL graft failure usually results from more than one factor. A new injury is the most common single cause. The most common technical cause is a bone tunnel in the wrong position, particularly in the thighbone (femur). [1] A steep posterior tibial slope (the backward tilt of the top of the shin bone) is now recognised as an important contributor. A steep slope makes a graft tear several times more likely. [2] [3] Other factors include meniscal deficiency, poor graft incorporation and, rarely, infection.
Who might need revision ACL surgery?
Not all failed grafts require surgery. A torn ACL graft does not heal to normal function on its own, but some people can manage without surgery if their knee remains stable and they avoid high-demand activities. Physiotherapy and strength training are part of this approach. However, ongoing instability increases the risk of further damage to the meniscus and cartilage.
Revision ACL surgery is typically considered when you have:
- Ongoing instability or giving way
- Recurrent swelling or pain
- A wish to return to sport or higher-level activity.
The decision to proceed with revision surgery depends on your symptoms, activity level and expectations.
What is involved in revision ACL surgery?
Revision ACL reconstruction is usually performed arthroscopically (keyhole surgery). Each step is planned carefully and tailored to the findings in your knee.
1. Assessment and planning
A thorough assessment is essential. This includes understanding how the graft failed (a contact or non-contact injury), reviewing the previous graft type and earlier operations, and checking for associated injuries, particularly to the meniscus.
Imaging typically includes:
- X-rays, to assess alignment and the posterior tibial slope
- MRI, to confirm graft rupture and assess the meniscus and cartilage
- A CT scan with 3D reconstructions, to assess tunnel position and widening.
2. Removal of the failed graft
The failed graft is removed, and the old bone tunnels are assessed and prepared.
3. One operation or two
Revision ACL surgery may be completed in a single operation or, when necessary, in two stages.
A single-stage revision is performed when the previous tunnels are well positioned and there is minimal tunnel widening. This allows the reconstruction to be completed in one operation.
A two-stage revision is needed when the tunnels are malpositioned or significantly widened. In the first stage, the tunnels are filled with bone graft. In the second stage, usually 4–6 months later, the ACL is reconstructed.
Staging is not a setback. In large studies, people who had a two-stage revision did at least as well as those who had one operation. [4] [5]
4. Placement of a new graft
Graft choice depends on your previous surgery, your anatomy and your goals. Options include the hamstring tendons, the patellar tendon (bone-tendon-bone), the quadriceps tendon and, in selected cases, a donor graft (allograft). Dr Vishal Pai prefers not to reuse the same type of graft in revision surgery, because the quality of the original graft may have contributed to its failure.
5. Treatment of associated injuries
The meniscus is an important secondary stabiliser of the knee. Ramp lesions, tears where the inner meniscus joins the joint lining at the back of the knee, are frequently overlooked and may lead to the graft failing. Traumatic meniscal root tears often need repair. Early signs of arthritis may also be present, and these can influence your outcome and the surgical plan.
6. Extra procedures to protect the graft
A lateral extra-articular procedure (LEAP) adds rotational control on the outer side of the knee and reduces stress on the new graft. There are two forms: a lateral tenodesis (LEAT) and an anterolateral ligament (ALL) reconstruction. A LEAP is commonly recommended in revision surgery, and adding one lowers the chance of the new graft failing. [6]
You can read more about a LEAP and its role in ACL surgery.
7. Bone realignment (osteotomy)
A steep posterior tibial slope places extra strain on the ACL graft. A slope-reducing osteotomy is usually considered when the slope is 12 degrees or more, especially if a graft has failed more than once. [7]
A high tibial osteotomy (HTO) may be added if you have varus (bow-legged) alignment and early arthritis on the inner side of the knee. Combined with revision ACL surgery, it can improve stability and offload the arthritic part of the knee to reduce pain. You can read more about realignment osteotomy.
How long does it take to recover from revision ACL surgery?
Recovery after revision surgery is generally slower than after a first ACL reconstruction, but it follows similar principles. Rehabilitation is criteria-based: you move to the next stage when your knee is ready, not on a fixed date. A structured rehabilitation program and consistent effort are important. For a stage-by-stage guide to recovery after a first ACL reconstruction, see ACL reconstruction recovery week by week.
As a rough guide:
- Two-stage revisionIf you need two stages, your ACL reconstruction is usually done 4–6 months after the bone grafting.
- Next dayYou will usually go home the day after surgery.
- 2–3 weeksMost people are able to stop using crutches. This takes longer if you also have a meniscal repair or an osteotomy.
- 8 weeksBy this stage, Dr Vishal Pai expects your knee to straighten fully and to bend beyond 90 degrees.
- 3–4 monthsYou can start gentle straight-line jogging if your gym-based strength training is going well.
- 12 months or laterYou can return to pivoting or contact sport once you have passed return-to-sport testing.
Swelling can last 3–6 months, and the knee can keep improving for 12–18 months.
What results can you expect?
Revision ACL surgery restores stability in most people, although results are generally less predictable than after a first reconstruction. About 6 in 100 new grafts fail within 5 years. Knee function is usually good, although not quite as good as after a first reconstruction. [8]
Many people return to sport, although the rate is lower than after a first ACL reconstruction. [9] About 3 in 4 return to some sport, but only about half get back to their previous level. [10] [11] More people returned to sport when a LEAP was added. [10]
Results are influenced by factors such as tunnel position, meniscal or cartilage injury, and whether extra procedures are performed to protect the graft.
What are the risks and complications?
Every operation carries risks, and Dr Vishal Pai goes through them with you before you decide. The main risks of revision ACL surgery are:
- Infection, which is uncommon but more likely than after a first ACL reconstruction [12]
- Blood clots in the leg, in about 1 in 200 people after ACL surgery [13]
- Stiffness or difficulty getting the knee fully straight, which occasionally needs a further procedure
- The new graft tearing or stretching again (see above)
- Pain or weakness where the graft was taken, or a numb patch on the inside of the leg after a hamstring graft, which usually settles
- If you need two stages, a second operation and a longer overall recovery.
Rarely, the nerve on the outer side of the knee (the common peroneal nerve) or the blood vessels behind the knee are damaged, or the kneecap breaks if the graft is taken with a block of kneecap bone. An osteotomy adds its own risks, such as the bone being slow to heal.
Some people don’t return to their previous level of sport, and the risk of arthritis later in life is higher than for people who have never injured their knee. You will receive a written information sheet with the full list of risks.
Where does Dr Vishal Pai consult and operate?
Dr Vishal Pai consults at Sandringham Orthopaedic Specialists, Suite 1, 60 Bay Road, Sandringham. He performs revision ACL reconstructions at Calvary Holmesglen Private Hospital, 490 South Road, Moorabbin, and The Avenue Hospital, 40 The Avenue, Windsor. Patients come from across Bayside, Glen Eira and the Mornington Peninsula, and some travel from regional Victoria.
References
Show all 13 referencesHide references
- Vermeijden HD et al. 2020. Trauma and femoral tunnel position are the most common failure modes of anterior cruciate ligament reconstruction: a systematic review. Knee Surgery, Sports Traumatology, Arthroscopy.
- Dan MJ et al. 2025. Posterior tibial slope ≥ 12°, static anterior tibial translation ≥ 5 mm, age < 18 and lateral meniscus tears are major risk factors for hamstrings graft rupture: a cohort analysis of ACL reconstruction using a selective approach to lateral extra-articular tenodesis (conference abstract). Orthopaedic Journal of Sports Medicine.
- Dejour D et al. 2025. Posterior tibial slope (PTS) reducing osteotomy should be considered in patients having primary ACL reconstruction if PTS is greater than 12–14 degrees. Arthroscopy.
- Nielsen TG et al. 2024. Single- or two-stage revision after failed ACL reconstruction: no differences in re-revision rates and clinical outcomes. Knee Surgery, Sports Traumatology, Arthroscopy.
- Mathew C et al. 2018. Single-stage versus two-stage revision anterior cruciate ligament reconstruction: a systematic review. Journal of ISAKOS.
- Boksh K et al. 2023. The role of anterolateral ligament reconstruction or lateral extra-articular tenodesis for revision anterior cruciate ligament reconstruction: a systematic review and meta-analysis of comparative clinical studies. The American Journal of Sports Medicine.
- Vivekanantha P et al. 2025. The commonest indication for performing a slope-reducing osteotomy with an anterior cruciate ligament reconstruction is graft failure with a posterior tibial slope 12 degrees or greater: a systematic review of indications, techniques, and outcomes. Arthroscopy.
- Mohan R et al. 2018. Clinical outcomes in revision anterior cruciate ligament reconstruction: a meta-analysis. Arthroscopy.
- Manojlović M et al. 2026. Return-to-sport outcomes and psychological readiness to return to sport after revision compared to the primary anterior cruciate ligament reconstruction: a systematic review and meta-analysis. Sports Medicine – Open.
- Gopinatth V et al. 2026. Return to sport after revision anterior cruciate ligament reconstruction: a systematic review and meta-analysis. The American Journal of Sports Medicine.
- Grassi A et al. 2015. After revision anterior cruciate ligament reconstruction, who returns to sport? A systematic review and meta-analysis. British Journal of Sports Medicine.
- Zhao D et al. 2022. Risk factors for postoperative surgical site infections after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. British Journal of Sports Medicine.
- Gaskill T et al. 2015. The prevalence of symptomatic deep venous thrombosis and pulmonary embolism after anterior cruciate ligament reconstruction. The American Journal of Sports Medicine.
Frequently asked questions
Is revision ACL surgery more difficult than the first surgery?
Yes. Revision surgery is more complex than the first ACL reconstruction. It requires careful assessment of the factors that led to the graft failing, including tunnel position, alignment, the meniscus, the posterior tibial slope and whether the reconstruction needs to be staged.
Dr Vishal Pai regularly performs revision ACL surgery.
Will I need one surgery or two for revision ACL reconstruction?
This depends on the position and condition of your current bone tunnels.
If the tunnels are well positioned and not significantly widened, a single-stage revision can be performed.
If the tunnels are malpositioned or significantly widened, a two-stage procedure is needed. Bone grafting is performed first, followed by the reconstruction several months later. Large studies have found similar results with both approaches when each is used in the right situation. [4]
What is tunnel widening and why does it matter?
Tunnel widening is the enlargement of the bone tunnels created during the first ACL surgery.
If the tunnels are too large, it is difficult to fix a new graft securely. In these cases, bone grafting may be needed before revision surgery can be performed. A CT scan is used when an ACL graft has failed to check tunnel position and whether tunnel widening has occurred.
What is the difference between ACL graft failure and stretching?
Graft failure usually refers to a complete rupture of the reconstructed ligament. Graft stretching means the ligament remains intact but has become lax, resulting in reduced stability.
Both can cause similar symptoms, but management may differ depending on the degree of instability and your activity goals.
When should I see a knee surgeon for a failed ACL reconstruction?
You should seek an assessment if you have:
- Ongoing instability or giving way
- Recurrent swelling or pain
- Difficulty returning to sport
- A new injury to a previously reconstructed knee.
Early assessment allows a more structured treatment plan and can help reduce the risk of further joint damage.
Next step
Talk through your options
If your ACL graft has failed or your knee feels unstable again, Dr Vishal Pai can examine your knee, review your scans and explain all your options, including treatment without surgery.