ACL Reconstruction

What is the ACL?

The anterior cruciate ligament (ACL) is a ligament in the middle of the knee that is very important in providing stability to the knee, especially in twisting movements.

How is it ruptured?

The ACL is often ruptured during a pivoting or twisting movement, usually while playing sport. It can also be caused by a blow to the outside of the knee when the knee is bent. Sometimes, it is caused by hyper-extending (over straightening) the knee, such as when jumping up and landing awkwardly.

What problems does an ACL rupture cause?

When the ACL ruptures, there is often sudden pain and the knee gives way. The knee typically swells significantly. The pain and swelling typically take a few weeks to resolve. The main problem that an ACL rupture causes is instability of the knee. If you are lucky, the ACL may heal well enough that it does not cause significant problems, especially if you do not play sport. Often, however, the knee may feel unstable or give way with twisting movements during sport or, in the worst cases, even when doing day to day activities.

Long term, if the knee is unstable, there is an increased risk of further injury to the cartilage within the knee and also arthritis.

How is an ACL rupture treated?

Immediately after a significant knee injury like an ACL rupture, applying ice to the knee is important, as it minimises swelling.

Resting and elevation are helpful and a period mobilising with crutches may be necessary.

Early review by an Orthopaedic Surgeon is recommended so that the knee can be assessed. Sometimes there may be other ligament or cartilage injuries that may also be present.

An MRI scan is helpful in confirming the extent of the injuries.

Physiotherapy should be commenced as early as possible to reduce swelling and regain muscle strength and range of motion at the knee.

Depending on your circumstances and the stability of the knee, the ACL rupture may be treated surgically or non-surgically.

Non-surgical treatment involves rehabilitating the knee and gradually returning to full activities. If you are able to return to all of your normal activities and the knee does not feel unstable, no further treatment is necessary.

If the knee is unstable or you wish to return to sports that involve a lot of twisting and pivoting or contact sports, non-surgical treatment is less likely to be successful. In that case, an ACL reconstruction is recommended.

What is an ACL reconstruction?

An ACL reconstruction involves using a graft to replace the ACL. There are several options available in terms of choosing a graft. The most common graft is created from two of the hamstring tendons from the back of the thigh. A small incision about 4cm long is made in the front of the knee through which the two tendons are taken. They are then doubled over and stitched together to form the new ACL. Two small portals (less than 1cm long) are made in the front of the knee to perform an arthroscopy. Any other injuries in the knee can be managed through these portals. Tunnels are drilled through the femur (thigh bone) and tibia (shin bone). The graft is then pulled up into the tunnels so that it lies in the position of the original ACL. The graft is fixed in place with buttons or screws. The wounds are then closed.

Current research shows that the success of the ACL reconstruction depends on the positioning of the tunnels. The surgeons at Melbourne Hip and Knee have trained with several world leaders in ACL surgery, in Australia, Europe and North America, to learn the most advanced techniques in ACL reconstruction, giving you the best chance of regaining stability in your knee.

What happens after my operation?

You will stay in hospital for one night to make sure that your pain is under control. You will be seen by a physiotherapist who will start your rehabilitation and will teach you to walk with crutches. You will have an x-ray of your knee to make sure that the devices used to fix the graft are in the right place. You will be discharged home soon after the x-ray has been taken. Your surgeon may not see you before you are discharged if there are no problems.

Pain Relief

During your procedure, your knee has been injected with Local Anaesthetic, when this wears off, you will feel more pain in the knee. The day after surgery may be more uncomfortable than the day of surgery. When taking pain medication, it is better to begin once the pain commences, rather than wait until it has built up.   It is best to start with regular paracetamol (2 tablets, every 6 hours). You may have been prescribed something stronger such as Panadeine forte, Tramadol, or Endone. Endone and Tramadol can be taken in addition to paracetamol. Panadeine forte is used instead of Panadol.

You may also have been prescribed anti-inflammatory medication. These should be taken with food. If you get indigestion or have ongoing nausea, the anti-inflammatory tablets should be stopped. It is usual to expect an increase in pain and swelling about four or five days after your procedure. Rest, ice, compression and elevation will help to reduce this.


Small tapes hold the small puncture wounds together. Waterproof plastic patches cover them, so you can shower directly on to the knee. Leave all dressings intact until your post operative review appointment which will be scheduled for approximately two weeks after surgery.


Swelling is common after an ACL reconstruction. Fluid in the joint results in generalized swelling and is most obvious above the kneecap. Swelling is also common around the incisions and this can take some months to resolve.

Applying the R.I.C.E. principles – rest, ice, compression, and elevation, will help swelling.

Rest: During the first 3 days you should rest with your leg elevated as much as possible. You can then generally increase your activity, guided by your pain and swelling.

Ice: For the first week you should try to ice your knee 3 times a day for 20 minutes. After this time ice the knee following exercise and at the end of the day until your swelling reduces.

Compression: You will usually have a Tubigrip stocking around your knee. Sometimes you will have a bandage. The bandage can be replaced by a compression stocking on the day after surgery. The compression stoking should be worn during the day until your swelling reduces (usually about 2-4 weeks)

Elevation: Elevating the leg will assist in reducing swelling.

Will I need crutches?

Unless otherwise instructed you can place as much weight on the leg as comfortable with the help of crutches for the first 2 to 3 days following surgery.

To start with, the pattern of walking is ‘crutches, bad leg, good leg’. Once you are more comfortable, the crutches and operated leg go forward together. You may find it easier to use just one crutch. Use it with the opposite arm i.e. for a left knee operation; use the crutch with your right arm.

To manage steps with crutches, use the following guide:

  • UP good leg, bad leg, crutches
  • DOWN – crutches, bad leg, good leg

If you already have your own crutches you can take them to hospital with you, otherwise the hospital will organise these for you.

Post-operative appointment

You will usually have a post-operative appointment booked to see your surgeon approximately two weeks after surgery.

Your appointment information is on your admission letter.

Please call Melbourne Hip and Knee if you are unable to locate this information.

How long is the recovery after an ACL reconstruction?

After an ACL reconstruction, you are encouraged to begin bending and straightening the knee immediately. You will be able to be discharged from hospital the morning after your operation.

You will be able to walk on the operated leg but will need crutches for 1-2 weeks.

It is very important that you attend physiotherapy sessions regularly and do the exercises daily. Your physiotherapist will monitor your progress and increase your exercises accordingly and guide you back to sport and will also teach you strategies to minimize the risk of further ACL injuries. The rehabilitation after an ACL reconstruction occurs over a long time.

Returning to activity

Driving: If you have had your left knee operated on and you drive an automatic car then you can drive when you are off all painkillers and you can easily get in and out of the car. If you have your left knee operated on and you drive a manual car you need to ensure that your knee is strong enough to use the pedals safely.

If you have your right knee operated on, your knee needs to be strong enough and move well enough, to quickly change pedals and push hard on the brake to perform an emergency stop. This can take one to two weeks.

Work: The amount of time you will need to take off work depends on the type of work you do. For desk-based jobs, you will need 2 weeks off. If your job involves heavy manual labour, you may require 2-3 months of leave.

Sport: It will take 3-4 months before you can cycle or jog and it can take 9-12 months to return to sport. It is important not to try to get ahead of the rehabilitation program as this may cause the graft to stretch out or rupture.