Prof. Cavaignac, a specialist in knee surgery and sports traumatology, is highly qualified to perform ACL surgery.
ACL Injury: Reconstruction
Rupture of the ACL is a common injury among people who engage in sports that stress the knee, especially in rotation. Knee ligament surgery is a minimally invasive procedure, performed under local or general anaesthesia, which involves reconstructing the ruptured ligament by replacing it with a piece of tendon taken from the patient. During the operation, the surgeon inspects all the structures of the knee to address any other injuries associated with the ACL injury.
To delve deeper into this topic, watch the talk “Management of Injuries of the Secondary Stabilizers of the Anterior Cruciate Ligament (ACL)” available on YouTube. Additionally, the scientific article “Epidemiology of Combined Injuries of the Secondary Stabilizers in ACL-Deficient Knees” offers a detailed analysis and data on combined injuries of the secondary stabilizers in patients with ACL tears. Available on ResearchGate.
What is the ACL and when is an ACL operation needed?
The ACL is located inside the knee joint and can be compared to an elastic band, when it is damaged, an ACL operation might be needed.
Why is it called “cruciate”?
There are actually two ligaments – the anterior cruciate ligament and the posterior cruciate ligament – that cross each other and work together to perform the same function: maintain the connection between the tibia and the femur, thereby stabilising the knee during flexion and extension movements or rotation of the leg.
Thus, the ACL prevents the tibia from moving or rotating too far relative to the femur, which would risk displacing the elements constituting the knee joint from their positions.
How do you know if your ACL is injured?
When the ACL is completely ruptured, an ACL reconstruction surgery may be required for patients to regain full usage of their knee.
Depending on the type of anterior cruciate ligament injury, the symptoms and their intensity can vary. Mobility is significantly reduced due to pain in the knee. Patients often describe a sensation of the knee “giving way” when walking or changing directions.
Symptoms and Diagnosis
The knee will be unstable, painful, swollen, locked, and walking will be difficult. A quick medical consultation is crucial.
After an X-ray, a magnetic resonance imaging (MRI) scan will help to refine the diagnosis. This will confirm (or rule out) rupture of the ACL and look for the presence of other potential injuries such as meniscal tears or collateral ligament injuries.
The most common symptom of an ACL injury is that patients feel intense pain when the injury occurs. This can cause them to stop the activity immediately. A “pop” or cracking sound may also occur, indicating a more severe injury. The inflammation caused by the injury can lead to swelling around the knee within hours. In some cases, it is difficult to put weight on the affected leg.
Why ACL reconstruction surgery?
It is important to know that a ruptured ACL cannot heal on its own, even if the knee is immobilised. That’s why ACL reconstruction operation is essential. In many cases, the patient will have an unstable knee that gives way, hindering daily movements, preventing sports activities, and increasing the risk meniscal injuries in the future, damage to other ligaments, cartilage degradation, and eventually, osteoarthritis.
ACL tear surgery is necessary to remove the laxity, stabilize the joint, and restore full function. The surgeon will reconstruct your ACL and treat any secondary injuries.
What is an ACL reconstruction surgery?
A ruptured ACL can be treated using a reconstruction surgery for a torn ACL. You can refer to the knee exploration video here.
Just before the operation, the surgeon will check the exact anatomy of your knee and its injuries using ultrasound imaging. This will allow him to adapt the surgery by adding lateral reinforcement, for example.
An ACL knee surgery involves replacing the ruptured ligament. This can be done by minimally invasive surgery, using arthroscopy. A camera is inserted into the knee through a small incision to visualize the ruptured ligament. Through other small incisions, surgical instruments are used to take part of a nearby tendon and use it to replace the ruptured ligament.
The tendon graft is then inserted into two small bone tunnels drilled in the femur and tibia. The specialist knee surgeon then fixes this tendon with resorbable screws or cortical supports – a system that attaches the tendon graft to the hard part of the femur, called the cortex.
In most cases, a second stabilisation procedure is necessary to ensure optimal knee stability. This involves using the gracilis to stabilize the anterolateral aspect of the knee.
For practical information, watch the video “ACL and ALL Reconstruction Technique with Hamstrings Using Independent Graft” on YouTube.
During knee ligament reconstruction surgery, any meniscal injuries will be treated at the same time. The tendon from which the graft was taken will heal quickly on its own. For a torn ACL, this operation usually lasts 30 minutes and is performed as an outpatient surgery (entry in the morning and exit in the evening).
What techniques can be used?
After an ACL injury, the type of operation can vary. Indeed, there are several techniques for performing this surgery, including the STG and ST4 methods.
STG uses two tendons: semitendinosus and gracilis. This approach is more invasive as it involves harvesting two tendons, which may potentially weaken the hamstring muscles. In contrast, ST4 uses only the semitendinosus tendon, sparing the gracilis tendon. This has the advantage of weakening the hamstring muscles less, which facilitates the postoperative rehabilitation.
Other techniques include using the patellar tendon (Kenneth Johns), the quadriceps tendon, or even an allograft.
The choice depends on several factors, including the surgeon’s preferences, the specific condition of the patient’s knee, and expectations regarding recovery and return to sports. Professor Etienne Cavaignac will discuss the options with you and suggest which surgical technique he feels is best for your case.
Graft options and lateral reinforcement in ACL reconstruction
Choosing the right graft is a key step in planning your ACL surgery.
The following graft types are those personally performed by Professor Cavaignac in ACL reconstruction. Each is chosen according to your anatomy, sport, and recovery goals. All procedures are arthroscopic and may include a lateral reinforcement (ALL or LET) to enhance rotational stability in pivoting sports.
Terminology at a glance
- ALL: Anterolateral ligament reconstruction (inside–out control of rotation)
- LET: Lateral extra-articular tenodesis (a reinforcement on the outside of the knee)
- ILT: A specific technique within the LET family used in our practice
- Pedicled: The tendon is kept attached at one end to preserve its blood supply
- Socketed: Short bone tunnels (“sockets”) that preserve bone stock
Hamstring grafts (DT3/ST4): standard options
Most primary ACL reconstructions are performed with your own hamstring tendon(s). These techniques preserve the patellar tendon and kneecap mechanics and usually allow a smooth rehabilitation.
DT3 pedicled, socketed ACL graft + independent ALL/LET
The semitendinosus is prepared as a triple-strand (DT3) graft, left attached at its tibial end (pedicled) and fixed in short bone sockets. A separate anterolateral reinforcement (ALL or LET) is added to better control rotation. This combination addresses both forward looseness and the “twist” that causes giving-way in cutting sports.
DT3 for the ACL + anterolateral reinforcement in the same sitting
Another frequently used approach is a DT3 ACL graft with a planned anterolateral procedure in the same operation. In our practice, the gracilis may be used for the anterolateral reinforcement when indicated, offering extra protection against rotational instability in higher-risk athletes.
Why sometimes choose ST4?
Where suitable, a quadruple-strand semitendinosus (ST4) lets us avoid harvesting the gracilis, which can help maintain hamstring strength.
Typical donor-site sensations with hamstring harvest
Temporary inner-thigh tightness or weakness is common early on and is addressed with targeted physiotherapy.
Other autograft options (selected cases)
When your sport, anatomy or previous surgery make hamstrings less suitable, we may recommend alternative autografts, most commonly the patellar tendon (BTB) or quadriceps tendon, when they offer clearer advantages for stability and recovery.
Patellar tendon (bone–patellar tendon–bone, “BTB”)
Useful in certain sports or anatomies; may be associated with anterior knee pain when kneeling.
Quadriceps tendon
A versatile option with robust graft size; front-of-thigh tenderness can occur initially.
The best choice is discussed with you after examination and imaging so that graft type, size and fixation match your knee and sporting aims.
Rectus femoris tendon graft
The Quad 2.0 Technique is a technique developed and published by Professor Cavaignac and his team.
This minimally invasive option offers a strong and consistent graft diameter, harvested through a small anterior incision, while sparing the hamstrings and patellar tendon.
Key advantages:
- Excellent graft strength comparable to hamstring autografts
- Preservation of hamstring function, ideal for athletes needing sprinting power
- Reduced anterior knee pain compared with BTB grafts
- Low donor-site morbidity and faster functional recovery
This graft may be proposed in cases of previous hamstring harvest, specific anatomical conditions, or to optimise return to sport performance.
Anterolateral reinforcement (ALL / LET / ILT)
To optimise knee stability, an anterolateral reinforcement is often performed at the same time as ACL reconstruction.
This complementary procedure aims to better control rotational movements of the knee, the “twisting” that can cause giving-way sensations in pivoting sports such as football, rugby, or skiing. It is particularly useful for young, competitive, or high-risk athletes, as well as for patients whose knees show increased laxity on examination.
Depending on each case, several reliable reinforcement techniques can be used.
ALL (Anterolateral Ligament Reconstruction)
This minimally invasive technique reconstructs the anterolateral ligament on the outer front of the knee. It acts like a rotational brake, providing additional control when turning or landing.
LET (Lateral Extra-Articular Tenodesis)
This method uses a strip of the iliotibial band to reinforce the outer aspect of the knee. It limits excessive internal rotation and significantly reduces the risk of re-injury during cutting or contact sports.
ILT (Isolated Lateral Tenodesis)
A refined form of LET developed in Professor Cavaignac’s practice, ILT provides targeted reinforcement of the lateral capsule while preserving natural knee motion. It is designed to stabilise the joint without over-tightening, helping protect the new graft and improve long-term outcomes.
In most patients, adding this anterolateral reinforcement provides greater rotational control, protects the reconstructed ligament during the early phases of recovery, and enhances confidence when returning to high-demand activities.
If you are unsure which option fits your sport and timeline, Professor Cavaignac will go through the pros and cons of each graft with you in consultation so you can make an informed decision together.