ACL injury, treatment & reconstruction Adelaide

ACL injury, treatment & reconstruction Adelaide

What is the ACL?

The knee is the largest and most complex joint in your entire body. It doesn’t just bend backwards and forwards like a simple hinge, it also rotates or pivots. The ligaments inside and outside the knee joint play an important role in preventing it moving too far in any one direction. This keeps your knee stable and stops it giving way. Unfortunately an ACL injury is relatively common.

The Anterior Cruciate Ligament, or ACL, is one of the most important stabilising ligaments in your knee joint. It connects the thigh bone (femur) to the shin bone (tibia) inside your knee joint.

The ACL’s main job is to stop your knee overrotating or pivoting. This is especially important when you are moving from side to side or changing direction quickly. These are the movements you would perform regularly in a variety of sports, especially if you were trying to dodge around an opponent. The ACL is also crucial when landing, such as after jumping up to catch a ball, then coming back down and planting your foot on the ground.

What happens when my ACL Ruptures?

Most ACL injuries are non-contact, which means you don’t usually collide with an opponent or receive a knock, your knee simply gives way without warning. The ACL can also rupture due to a direct blow or collision.

The ACL does not need to completely rupture to cause your knee to be unstable. An over-stretched ACL (even it if doesn’t completely tear in half) will not return to the same level of ‘spring’ or elasticity. Just like an over-stretched rubber band, it can no longer spring back to its original shape and tension. This may be reported as an ‘ACL strain’ on an MRI scan. But in most situations the remaining ACL is completely non-functional. Many ACL injuries present like this. A torn or over-stretched ACL is unable to heal or repair itself. It will never return to the same shape and function.

An ACL injury involves the entire knee joint, not just the torn ACL. When the ACL ruptures, the thigh bone and shin bone collide heavily with each other. This causes bleeding and bruising to the bone beneath the cartilage in your knee joint. Living bone is not dry and lifeless like a skeleton in a museum, it is full of blood and other nutrients, and it bleeds when injured. It may take 6 months or more for this bone bruising to resolve. This is one of the reasons ACL recovery does not happen overnight.

The same force that causes bone bleeding is also transmitted into the smooth articular cartilage that covers the ends of the knee bones. Unlike bone, cartilage cannot repair itself back to normal. It is likely that the force the cartilage was exposed to plays a role in some patients developing arthritis in their knee, even many years after an ACL injury.

I’ve just injured my ACL- what now?

1. Speak to your General Practitioner or pharmacist for advice on pain management, but in general take regular anti-inflammatory medication along with Panadol for 3-5 days. It is safe for most patients to take both these medications together.

2. Apply a compression bandage or stocking to your knee and elevate it as much as possible. These are available from your physiotherapist or chemist. You DO NOT need to buy a rigid knee brace.

3. Ice your knee as often as possible. Usually 20- 30 minutes of ice, followed by 30-60 minutes without ice, repeated throughout the day.

4. Unless you have been specifically instructed by an experienced sports doctor or orthopaedic surgeon, DO NOT keep your knee in a rigid brace. These usually do more harm than good and lead to weakness and stiffness.

5. Bend and straighten your knee as much as possible – you’re not going to do any further damage by doing this. You won’t like the feeling of trying to get your knee fully straight, but gently try to achieve this.

6. Walk on your knee if pain, swelling and strength allows. Use crutches to help you gradually put more and more weight through your knee. The more weight you can put through your knee the better.

7. Make an appointment with an experienced sports physiotherapist – the sooner you start rehabilitation (or prehabilitation if you end up having surgery) the better your recovery will be. There is a list of recommended physiotherapists, in various locations, on my website.

8. Talk to your General Practitioner and physiotherapist about recommending an orthopaedic surgeon. Even if you don’t end up needing surgery, it is very important that you see a surgeon to have them examine your knee, review your MRI images and talk to you about your options. Try to find an orthopaedic surgeon who regularly performs a high-volume of ACL reconstruction surgery.

9. It is usually recommended to let your knee swelling settle and range of motion improve for 1-2 weeks prior to ACL surgery. So, don’t worry if it takes some time to see your specialist. You’re not doing any harm waiting, and it gives you time to think about your options. You are not obligated to see any particular surgeon, no matter where your injury was first assessed. It’s your knee, and you are in full control of your treatment

Download and read Dr Matthew Hutchinson’s guide of what to do if you just injured your ACL.

What is an ACL Reconstruction?

Because the ACL is so badly damaged when it ruptures, it is unable to be repaired or sewn back together. It will not heal anywhere near enough to function normally. An ACL reconstruction is required. This completely replaces the ruptured ACL with something else. Your surgeon ‘borrows’ a tendon from somewhere else in your body, to take the place of your injured ACL. We call this borrowed tendon a graft.

There are a number of good graft options for ACL reconstruction, and these include your hamstring tendon, kneecap tendon (patella tendon) and quadriceps tendon. Your surgeon can discuss which option is most suitable for you. In Australia, hamstring ACL reconstruction is the most common.

Synthetic ligaments, such as a LARS ligament, are an option. But I do not recommend them as their long-term results have been inferior.

In Growing Athletes, there is also the option for Mum or Dad to donate one of their hamstring tendons to reconstruct their child’s knee. I do offer this option, but in general it is only recommended in younger children.

For the purposes of this fact sheet, I will refer to hamstring ACL reconstruction because it is the most common. No matter what graft your surgeon uses, the basic principles are the same. I offer all options for my patients, depending on what is most suitable for them.

Surgery takes place through 3 key-hole incisions. Two small incisions about 5mm in size either side of the kneecap, and one incision about 3cm in length on the inside of your shin. Several months after surgery these scars are almost unnoticeable.

Do I need ACL Surgery?

In general, younger patients who wish to return to high demand occupations or sports/hobbies that involve side-to-side movements, should consider ACL reconstruction. Older patients who have an active lifestyle, especially if their bobbies involve side to side movement, may also need to consider ACL reconstruction.

Patients with an acute meniscal tear, in most age groups, should strongly consider ACL surgery. The meniscal tear will not heal unless it is repaired. Meniscal healing rates, without ACL reconstruction at the same time, are very poor.

In general, older patients who do not have a demanding manual job or enjoy sports/hobbies that involve side to side movement, may cope well without ACL surgery. Your physiotherapist can implement a rehabilitation program to strengthen and better coordinate your knee muscles, to compensate for your ACL injury.

It may be 6 months or more until we know if this physiotherapy treatment has been successful, and this is gauged by whether or not your knee is giving way during the activities you perform in everyday life.

With this non-surgical approach, it is recommended that you do not participate in sports/hobbies that involve side to side movements, as there is a considerable risk your knee will give way again. This could lead to more damage to your articular cartilage and meniscus. If nonoperative management of your ACL injury fails, then a delayed ACL reconstruction can still be performed at any time in the future.

Recovery after ACL Surgery and ACL Injury

You will usually be in hospital for one evening after surgery, but day surgery is also an option.

After surgery you will feel some discomfort up the back of your thigh and behind your knee. This is where your hamstring has been harvested from. You will also have swelling and discomfort in your knee.

You are encouraged to mobilise on your knee as soon as you feel comfortable. You can put as much weight through it as you like, but most patients will need to use crutches for 3-7 days until they can safely walk without them. Your physiotherapist will guide this process.

2 weeks off work is recommended for most patients. You may be able to return to light, officebased duties within one week. You may have pain and swelling if you spend long periods of time on your feet.

You could drive a car within 1-2 weeks, depending on your pain and swelling and also which leg you have had surgery on. You need to be able to get into and out of the car and operate the vehicle safely. Your physiotherapist can guide this process.

During your hospital visit you well be seen by a sports physiotherapist, and they will get you started with a 2-week rehabilitation program, by showing you exercises that you should perform at least 3 times per day.

Rehabilitation is essential when recovering from ACL reconstruction. Patients who do not put in a regular effort, overseen by an experienced sports physiotherapist, can expect much poorer results.

Full ACL rehabilitation takes a minimum of 12 months. And maintaining a regular injury prevention program with your physiotherapist is also highly recommended.

Good ACL rehabilitation is not time-focused, it is goal-focused. We don’t accelerate your rehabilitation purely according to how long it has been since your surgery. You progress is based on achieving goals. These might include range of motion, swelling reduction or strength improvement, for example.

Download and read Dr Matthew Hutchinson’s in depth guide for ACL Rehabilitation Protocol.

Timeline for ACL Injury Recovery


Walking without crutches, but you may still have a limp. You can cycle on an exercise trainer as soon as your knee has sufficient bending.

Download and read Dr Matthew Hutchinson’s in depth guide to the first 2 weeks after ACL Surgery.


Full range of motion, reduced swelling and walking without a major limp.


Jogging in a straight line.


Jumping, landing and leaping under the direction of your physiotherapist.


Sports-specific training: doing some of the activities of your chosen sport, but in a non-contact environment.


Training and activities will gradually progress, with the aim of retuning to full sports by approximately 12 months.

Risks of ACL Reconstruction Surgery

ACL reconstruction is safe and effective, for patients of all ages, and most complications are rare. However, like any operation there are some risks involved. Below is a summary of these complications, but you should discuss these further with your surgeon.

Skin Infection

Occurs in less than one percent of patients and is usually mild. You may require some tablet antibiotics but there would be no long-term consequences.

Deep Infection within the Knee Joint

Occurs very rarely; approximately 1 in a thousand patients. If this occurred you would require another key-hole operation to wash the infection out, and antibiotics for a number of weeks.

Numbness of Skin

It is not uncommon for patients to have a ‘numb patch’ of skin on the outside of their leg. This is due to very small nerves being cut when the skin incision is made on your leg. This will cause no functional problems, but it may feel unusual. It may improve significantly over a 6-month period. Taking 500mg of vitamin C twice a day for 3 months will assist this recovery (250mg twice a day for children under 16 years of age).


It may take 2-6 weeks for you to get your knee fully straight. Ideally, you would achieve this by 2 weeks, but in some patients this takes longer. Pain, swelling and scar tissue formation within the knee can all limit this. If your knee remained stiff for 3 months or longer then you may require another key-hole operation to remove scar tissue from within your knee joint, to improve your range of motion. Rarely, a patient may never regain their full knee straightening.

Blood Clot/DVT

The risk of a blood clot, or DVT, is low after an ACL reconstruction. Most patients will not require any blood thinning medication.

ACL Re-Rupture

There is a risk that you could re-rupture your reconstructed ACL. The risk of re-rupture depends upon your age, gender, type of sport you wish to return to, and also how much time and effort you put into rehabilitation. You are more likely to rupture the ACL in your other, non-injured, knee than you are your reconstructed knee. Well performed surgery and quality rehabilitation are the two most important factors in preventing ACL re-rupture. If you did re-rupture your reconstructed knee, then it can be reconstructed again. The recovery is the same as the original procedure.


Swelling can persist within your knee for several months. It takes 12 months for the graft to fully heal inside your knee, and as long as on-going healing is occurring there can be associated swelling. Your knee is also recovering from the bone and cartilage bruising that occurred during the initial injury. As you return to training and sports your knee may also swell as it adjusts to increasing loads.

Pain and Arthritis

There is a longer-term risk of pain and arthritis within your knee, largely due to the bone and cartilage bruising that occurred at the time of injury. A severe meniscus or articular cartilage injury will also increase your lifetime risk of arthritis.

Meniscus Tears with ACL Injury

A meniscus is horse-shoe shaped shock-absorbing cartilage pad within the knee joint. They are completely different to the articular cartilage that covers the ends of the knee bones. A meniscus is made from a rubbery form of cartilage called ‘fibrocartilage’. They are not just shock absorbers; they also play an important role in stabilising your knee joint. If a meniscus is permanently damaged, and eventually requires removal from your knee joint, you can develop arthritis quite rapidly, at any age. Meniscal tears are commonly associated with ACL injury.

The majority of meniscal tears will never heal unless they are surgically repaired. Meniscal tears associated with an ACL injury are even less likely to heal without surgery. Surgical repair of a meniscal tear is time sensitive. Meniscal tears left longer than 6-12 weeks before surgical repair are unlikely to ever heal.

ACL Reconstruction in Growing Athletes/Children

Growing Athletes, or school-aged children, have a predictably poor outcome without ACL reconstruction surgery. Even if these patients don’t play sports, the high demands of their young age and lifestyle often leads to ongoing instability of their knee. This causes further cartilage and meniscal damage, and there is a risk of knee arthritis later in life. Of course, every child is different, but in general this is my recommendation.

ACL reconstruction in children is safe and effective. I perform ACL reconstruction in children as young as 8 years of age, but fortunately ACL injury in this age group is quite rare. The bulk of the ACL injuries we see in children occur in adolescence. Because children are still growing there are some additional risks that you need to discuss with your surgeon, but these risks are very low.

When treating Growing Athletes, I focus a lot of time and attention actually talking with that young patient. Although Mum and Dad’s opinions and questions are very important, at the end of the day we need your child to take ownership of their injury, and their recovery. And the best way of achieving this is to allow them to make informed decisions about their own knee. Of course, Mum and Dad, and your surgeon, will play an important role in helping them make a decision, but they need to feel confident that they are in control.

Approximately half of the ACL reconstructions I perform are in Growing Athletes. And being a parent myself, I can understand how much stress and anxiety an ACL injury causes Mum and Dad. But I am constantly amazed at how well children cope with the surgery and recovery.

Children are not just ‘little adults’ and it is my recommendation that ACL reconstruction in Growing Athletes should be performed by orthopaedic surgeons with specific, sub-specialist training in paediatric ACL reconstruction. Ask your surgeon if they have this level of training, and what their experience is within this area.

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