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. As a result, the recovery and return to sports following ACL repair surgery is quicker than an ACL reconstruction. Short-term studies have shown favourable results following ACL repair surgery.

For a succesful ACL repair, the location of the tear must be near the origin of the ACL from its attachment to the femur.

An ACL repair uses stitches through the ACL tissue secured to a button. The repair is protected with synthetic tape to allow the ACL to heal.

What is involved in ACL repair surgery?

The steps involved in anterior cruciate ligament reconstruction surgery include:

1. Knee arthroscopy

Key-hole 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 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 bone using a bone anchor.

What is my follow-up schedule after the operation?

Approximately 3-4 weeks of leave from work is required for a desk-based job.

2 weeks

The wound dressings will be removed, and the wound will be reviewed to ensure it has healed. The sutures will be removed at this stage.

8 weeks

The range of motion in the knee will be assessed. It is expected that you will be able to fully straighten the knee and bend it more than ninety degrees.

6 months

After the completion of a supervised post-operative course of rehabilitation, a referral is made for return to play testing to ensure you are safe to return to sport.

Frequently Asked Questions

What are the risks of having ACL repair surgery? +

General complications of ACL reconstruction surgery can include:

Infection

The risk is less than 1 in 400 of developing an infection. This can occur despite using a sterile surgical technique, giving pre-operative intravenous antibiotics, and soaking the graft tissue in antibiotics.

If the infection involves only the wound (superficial), it may just need treatment with a course of antibiotics.

If a deep knee joint infection occurs, it may require more surgery to wash out the knee as well as intravenous antibiotics. If the infection fails to resolve after this, the graft tissue may require removal.

Deep vein thrombosis and pulmonary embolism

Clots can occur in the deep veins of the leg that may dislodge and occlude the arteries in the lungs. DVT presents as leg pain and swelling after your operation. The diagnosis is confirmed with an ultrasound scan and, depending on the type of DVT, may require treatment with blood thinners.

Bleeding and haematoma formation

Small vessels at the surgical site continue to bleed post-operatively and cause swelling, bruising, and pain. Although most cases resolve with time, some will require a washout of the pooled blood beneath the surgical wounds.

Specific complications of ACL repair surgery can include:

Saphenous nerve damage

This can occur when the hamstrings are harvested and will result in a numb patch on the inside of the leg. This usually improves with time but occasionally can be permanent. This does not affect the function of the ACL graft.

Difficulty kneeling

Patella tendon harvest is performed with an incision directly over the tendon at the front of the knee. As a result of the incision and the location of the graft, kneeling on the operated knee is sometimes poorly tolerated.

Repair re-rupture

Despite adequate rehabilitation, an ACL repair may fail. The rate of repair failure is 10% and is slightly higher than an ACL reconstruction. If this occurs, Mr Pai will talk to you about the option of performing ACL reconstruction surgery.

Stiffness

The knee can become stiff after surgery due to the formation of scar tissue. This stiffness usually resolves with physiotherapy but can sometimes persist. If the knee is not bending or straightening adequately 6-8 weeks post-operatively, a manipulation procedure may be required. This involves putting the patient to sleep and pushing on the knee in order to break the scar tissue.

Long-term osteoarthritis

Despite having an ACL repair, the risk of developing osteoarthritis in the long term is higher than for the general population. This is because the cartilage damage that occurs at the time of injury is irreversible.

What patients would benefit from an ACL repair +

The tear location is essential in determining the suitability of an ACL repair. The best outcomes are achieved when the ACL is torn directly from the femur. This is called a proximal ACL tear. Unlike an ACL reconstruction, the outcomes of ACL repair are better when it is performed soon after the injury (ideally within 3 months). If you have an ACL tear, a prompt opinion from a knee specialist is suggested to facilitate early treatment if required.

What are the advantages of ACL repair over a reconstruction? An ACL repair preserves the native ACL tissue and improves proprioceptive feedback (sense of body awareness in relation to itself and the environment). Due to this, there is no need to harvest a graft (hamstrings, quadriceps or patellar tendon) and the complications following this are avoided. Smaller bony tunnels are drilled compared to an ACL reconstruction which means less post-operative pain. An ACL repair results in a faster recovery, improved early range of motion and a more natural feeling knee.

What is the success rate of ACL repair? +

Although ACL repair surgery is highly successful, there is a risk that the repair site can be reinjured. The risk of this is approximately 10% and is higher that the risk of reinjury following an ACL reconstruction. Most patients that have an ACL repair recover faster, have a great range of motion and get back to sports earlier than those that have an ACL reconstruction.

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 for the first few weeks as the repair needs to be protected. However, thereafter you will resume your ACL rehabilitation as normal.

What happens if I reinjure my ACL repair? +

The risk of reinjury following ACL repair is 10%. If this occurs, an ACL reconstruction surgery can be performed and no bridges have been burnt. Patients having an ACL reconstruction after ACL repair surgery perform just as well as those who have only had ACL reconstruction surgery.

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 walk after an ACL repair? +

You will be walking and bearing weight with crutches on the day of surgery after an ACL repair. Crutches are used to make walking and bearing weight comfortable. Most patients require them for 1-2 weeks after surgery. A post-operative brace is required till you can confidently control your quadricep muscles. If a concurrent meniscal repair was performed, you may require up to a 6-week period of not bearing weight on the operated side.

When can I drive after an ACL repair +

You will not be able to drive for 6 weeks following an ACL repair. You must be off strong painkillers, be walking without crutches and have a relatively painfree range of motion in the affected knee before your commence driving.

When can I swim after an ACL repair? +

The wound should be kept dry for two weeks following the operation. Once the wound healing is reviewed at your 2-week post-operative consultation you will be able to shower with no wound dressings on. Participating in pool based rehabilitation or swimming is not recommended for 4 weeks after your operation as it may increase the risk of infection.

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 the athletes muscle strength and control has returned to near-normal levels before returning to sport. This usually occurs at a minimum of 6 months after the operation.