Reviewed by Dr Vishal Pai
An ACL repair stitches a torn anterior cruciate ligament (ACL) back onto the thighbone, instead of replacing it with a tendon graft as in an ACL reconstruction. This page covers which tears suit repair, what the operation involves, recovery, results and risks.
At a Glance
- An ACL repair re-attaches your own torn ACL to the thighbone (femur). No graft is needed.
- It suits only some tears: a recent tear close to the thighbone, with good-quality ligament tissue.
- If the tear can’t be repaired once the knee is seen during surgery, an ACL reconstruction is done under the same anaesthetic.
- About 1 in 10 repairs fail, and the risk is higher in younger people.
- Return to sport is usually no earlier than 6 months, once strength and control have returned.
What is an ACL repair?
An anterior cruciate ligament (ACL) tear or rupture can lead to symptoms of knee instability. If untreated, these episodes of instability can potentially result in secondary damage to the menisci in the knee and cause accelerated arthritis. Traditionally, an ACL reconstruction is performed to restore stability to the knee. This involves harvesting a graft to form the new ACL.
The location of the ACL tear is critical in determining whether an ACL repair is suitable. When the ACL tear occurs close to the thigh bone (femur), there is an option to repair the tear. A graft is not required because your ACL tissue is re-attached to the bone.
Who might need an ACL repair?
An ACL repair suits only some tears. The ACL needs to have torn close to the thighbone (a proximal tear), and the ligament tissue needs to be in good condition. Dr Vishal Pai checks this on your MRI scan and when he examines your knee.
Timing matters. A repair can be done up to 3 months after the injury, but within 4 weeks is preferable, so it helps to have an ACL injury assessed promptly.
Age matters too. Repairs fail many times more often in people aged 21 or under than in older adults. [1] For this reason, an ACL repair is generally not the preferred option for younger people.
What is involved in ACL repair surgery?
The steps involved in anterior cruciate ligament repair include:
1. Knee arthroscopy
Keyhole surgery is performed to confirm the ACL tear and identify secondary injury to the cartilage and meniscus. Any secondary injuries are treated during the same procedure. The location of the tear will determine whether the ACL can be repaired. If the tear location or tissue quality is not suitable for repair, an ACL reconstruction will be performed instead.
2. Tunnel drilling
Small bone tunnels are created within the femur and tibia (shin bone) in a location that simulates ACL origin and insertion. The tunnels are required to allow passage of a synthetic tape (Arthrex InternalBrace) that will protect the ACL repair site while it is healing.
3. ACL preparation and repair
Luggage tag stitches are passed through the native ACL to grasp the ACL tissue. These stitches are attached to a small metallic button (Arthrex TightRope) that anchors on the side of the thigh bone. Once the stitches are tensioned, the torn ACL is drawn up and reattached to the femur.
4. Fixation of the synthetic tape
The synthetic tape is passed through the bone tunnels and fixed into the tibia using a bone anchor.
How long does it take to recover from an ACL repair?
Physiotherapy starts after your first post-operative visit. It focuses on getting your knee fully straight, strengthening your thigh muscles and settling the swelling. Avoid resting with a pillow under your knee. You wear a brace until your thigh muscles are working well. Swelling can last 3 to 6 months. As a rough guide:
- Day of surgeryYou can walk and put weight on your leg with crutches on the day of surgery.
- Next dayYou will usually go home the morning after surgery, once a check X-ray has been taken.
- 2 weeksYour wound is checked at your first follow-up appointment. Most people with an office-based job are able to return to work.
- 2 to 3 weeksMost people are able to stop using crutches.
- 6 weeksYou may return to driving. People in physically demanding jobs can usually return to work.
- 8 weeksBy this stage, Dr Vishal Pai expects your knee to straighten fully and to bend beyond 90 degrees.
- 6 monthsYou are referred for return-to-sport testing. If you pass, you can begin a gradual return to sport.
- 12 monthsMost people reach their final result at around 12 months.
If a meniscal tear is repaired at the same time, you may need to avoid putting weight on the leg for up to 6 weeks.
What results can you expect?
Most people report good knee function after an ACL repair, at least in the first few years. [2] [3] The risk of the repair failing is higher in younger people. [4]
Compared with an ACL reconstruction, knee scores are similar, but a repair is more likely to fail. [5] People who had a repair returned to sport a little sooner. [6] Trials limited to recent tears found a smaller difference in failure. [7]
Most studies have followed people for only 2 to 5 years, so long-term results are not yet known. These figures are averages, not one surgeon’s results.
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 an ACL repair are:
- The repair tearing again, in about 1 in 10 people, and more often in younger people [1]
- Infection, in about 1 in 1,000 people
- Blood clots in the leg
- Bleeding into the knee, which occasionally needs a return to theatre to wash it out
- Stiffness, which occasionally needs a manipulation under anaesthetic if the knee is not bending or straightening by 6 to 8 weeks
- A numb patch on the inside of the leg, which usually improves with time, and some difficulty kneeling
A small number of people need a further operation, usually to remove the button or tape. [3] Rarely, a deep infection means the synthetic tape has to be removed. The risk of arthritis later in life is higher than for people who have never injured their knee, because cartilage damage at the time of injury cannot be reversed. 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 ACL repairs 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 10 referencesHide references
- Vermeijden HD et al. 2020. Role of age on success of arthroscopic primary repair of proximal anterior cruciate ligament tears. Arthroscopy.
- Wilson WT et al. 2022. Anterior cruciate ligament repair with internal brace augmentation: a systematic review. The Knee.
- Carrozzo A et al. 2025. Suture-augmented primary anterior cruciate ligament repair with internal brace shows acceptable re-rupture rates, favourable outcomes and high return-to-sport rates: a systematic review. Journal of Experimental Orthopaedics.
- Vermeijden HD et al. 2022. Primary repair with suture augmentation for proximal anterior cruciate ligament tears: a systematic review with meta-analysis. The Knee.
- Kunze KN et al. 2024. Clinical results of primary repair versus reconstruction of the anterior cruciate ligament: a systematic review and meta-analysis of contemporary trials. Orthopaedic Journal of Sports Medicine.
- Annibaldi A et al. 2025. Return to sport and clinical outcomes after arthroscopic anterior cruciate ligament repair versus reconstruction: a systematic review and meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy.
- Zhang T et al. 2025. Can repair be an alternative to reconstruction in the management of acute anterior cruciate ligament rupture: a meta-analysis of randomized controlled trials. Journal of Experimental Orthopaedics.
- Ren Y et al. 2024. Comparison of clinical outcomes between modern augmented ACL repair and autograft ACL reconstruction: a systematic review and meta-analysis of studies with minimum 2-year follow-up. Orthopaedic Journal of Sports Medicine.
- Rilk S et al. 2024. Anterior cruciate ligament primary repair revision rates are increased in skeletally mature patients under the age of 21 compared to reconstruction, while adults (>21 years) show no significant difference: a systematic review and meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy.
- Fradin T et al. 2021. Arthroscopic ACL reconstruction after failed ACL repair. Arthroscopy Techniques.
Frequently asked questions
Is an ACL repair better than an ACL reconstruction?
An ACL repair preserves your own ACL tissue, so there is no need to harvest a graft (hamstrings, quadriceps or patellar tendon), and the problems associated with taking a graft do not arise. Smaller bony tunnels are drilled than in an ACL reconstruction. Studies suggest people return to sport a little sooner after a repair, [6] keep more hamstring strength [8] and are less aware of their knee day to day. [9] The trade-off is a higher chance of the repair failing.
I have a torn meniscus as well as an ACL injury. Will you repair the meniscus at the same time?
Preserving and repairing the meniscus is always preferable to removing it. The meniscus acts like a cushion to support your cartilage. Having a torn meniscus is a common associated injury when you have an ACL tear. Any meniscal tears will be treated at the same time as your ACL repair. If a meniscal repair is performed, it will slow your rehabilitation in the early weeks after surgery as the repair needs to be protected. However, thereafter you will resume your ACL rehabilitation as normal. Read more about meniscal repair.
What happens if I reinjure my ACL repair?
About 1 in 10 ACL repairs fail, and the risk is higher in younger people. If this occurs, ACL reconstruction surgery can be performed. Because no graft was taken for the repair, all the usual graft options remain available. [10]
What happens if you are unable to repair the ACL during surgery?
The first step of the procedure is to perform a diagnostic keyhole surgery to confirm the suitability of an ACL repair. If an ACL repair is not feasible, an ACL reconstruction will be performed during the same anaesthetic.
When can I return to playing sport after an ACL repair?
There are various factors that determine when someone can return to playing competitive sport after having an ACL repair. It is crucial to make sure that the ACL repair has healed adequately and that muscle strength and control have returned to near-normal levels before returning to sport. This usually occurs at a minimum of 6 months after the operation, and you are referred for return-to-sport testing at that stage. In one review, people returned to sport at about 9 to 10 months on average. [3]
Next step
Talk through your options
If you are weighing up an ACL repair, Dr Vishal Pai can examine your knee, review your scans and explain all your options, including treatment without surgery.