Anterior Cruciate Reconstruction (ACL)

The Procedure

The anterior cruciate ligament (ACL) is one of the main restraining ligaments in the knee. It runs through the centre of the knee from the back of the femur (thigh bone) to the front of the tibia (shin bone) and it acts as a link mechanism between the thigh and lower leg.

The main function of the ACL is in stabilising the knee especially in rotation movements and sidestepping, cutting or pivoting manoeuvres.

This means that when the ACL is ruptured or torn the tibia moves abnormally on the femur and almost jumps out of joint such that the knee buckles or gives way.

The main feeling is a sense of the knee giving way on twisting or pivoting movements and a feeling of not trusting the knee. It is usual for individuals to be able to return to walking and straight line running following a torn ACL but to not trust the knee on rough ground or twisting movements.

The Surgery

The operation takes about one to one and a half hours depending often on other injuries in the knee – which are treated at the same time.

There are two options for the tissue to make a new ligament:


These are the most commonly used by me. The tendons taken are responsible for only a small part of the strength of the hamstring muscles. They produce a small scar and apart from some feeling of a “hamstring tear” for some time, cause few problems. If you have had a significant torn hamstring in the past, have other ligament injuries or looseness or wish to return to high level activities at a very early stage, patella tendon may be preferred.


This works just as well but is more painful after the operation. It involves a bigger scar and may cause problems with kneeling in the future. In some cases it is preferred but usually I use it for revision surgery or if multiple ligaments are involved.

Do you need a knee reconstruction?

The main role of a cruciate reconstruction is to prevent your knee from giving way.
If you wish to return to pivoting or twisting sports you will need a new ligament.
If you are happy to reduce your activity levels and avoid twisting, you may cope without an ACL– building up your thigh and hamstring muscles will help. Some people will find that there knee gives way even with simple day to day activities; – if this is the case a reconstruction of the cruciate is required.

Braces are available as an option and some people wear them for limited periods, eg whilst snow skiing. They cannot be worn for contact sports and usually are not tolerated for regular use.

What happens if I don’t have a reconstruction?

If your knee does not give way, you will do well but may still develop arthritis (Usually after 20 or so years) as a result of the initial injury.

If your knee gives way, as well as limiting your activities and causing discomfort, over time (Often within 12 months) you are likely to tear or rupture one of your meniscal cartilages. This often requires arthroscopic surgery and may increase the chance of developing arthritis.

What is involved in a surgical reconstruction of the anterior cruciate ligament?

Surgery can be performed anytime beyond the first week or two after the injury to allow the inflammation and pain from the injury to settle. You may spend some of this time in a brace, if you have ruptured another ligament (eg medial) Sometimes other ligament injuries necessitate earlier surgery.

Usually an MRI scan would be performed to plan treatment if injuries as well as the ACL rupture are apparent.

Following your surgery

When you return to the ward, you will be resting in bed. You will have a drip in your arm for fluids. You will have a bulky dressing over the wound on your knee.

A physiotherapist will see you on the morning following surgery and teach you to walk fully weight bearing on that leg with crutches.

Most people stay in hospital for one night; two nights is sometimes needed, usually if pain or post operative vomiting is a problem.

Crutches are used for a few days. By three weeks most people would be comfortable in an office job, six weeks for an active job and three months for heavy work.

The rehab involves ongoing physio – starting after two weeks when I have reviewed your wounds and knee. A detailed programme is outlined below..

At the end of the operation the knee is local anaesthetic is placed in the knee joint that lasts for up to 24 hours. It is not unusual for the knee to become more painful at around this time as the anaesthetic wears off. You will be supplied with strong oral analgesics (Tramal or Panadeine Forte) that may be required over the first few days. Please take these only as directed. Take one Aspirin tablet (300mg) each day for clot prevention.

How soon can I…

For the first ten days following the surgery, expect to be mobile at home using crutches, but resting otherwise, doing your exercises. After this your mobility will improve, but you should avoid any prolonged car or air travel for at least three weeks.
Wound Care – Yo should apply ice to your knee with your leg elevated. Place an ice pack on the bandages; 20minutes each hour. The bandages can be removed for showering after 48 hours from operation. (ie on Friday after Wednesday Surgery) Leave the other dressings and steristrips over the wounds in place.

You will be commenced on a single aspirin tablet a day (300mg daily) to be taken with food. This will be continued for six weeks or until mobile, and is taken to help thin the blood slightly and prevent blood clots in the legs or elsewhere. You should do foot and ankle pumps for five minutes in each 1⁄2 hour

Dr Sterling’s secretary will usually make your first post operative appointment prior to your surgery. You need to see Dr Sterling ten to fourteen days following your operation. If you do not have an appointment please phone to make one.

Most people are fit to return to sedentary (Office) type employment after two to three weeks. Expect six weeks before being fully mobile and able to stand all day and up to three months for heavy manual work such as labouring or gardening etc.

The basic expectation is that by;

  • 6 weeks – Walking normally with good endurance. 90% normal movement commence pool and gym work
  • 3 months – Straight line running begins. Controlled stepping with physio
  • 6 months – Individual pivoting sports (Non opposed eg shooting baskets)
  • 9 months – Return to sport

If you are concerned

You may have moderate pain following the surgery and can take panadeine forte as provided or paracetamol. The pain should lessen each day. You should contact Dr Sterling (through the switchboard of the hospital where you had your surgery), or his secretary on 1300 478 375. Whilst it is unlikely, if you feel extremely unwell, or there is an unexpected delay in finding Dr Sterling, attend the nearest Hospital Emergency Department.

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