Is ACL surgery the only way? Why knee exercise may trump for ACL injury!

ACL tear shown in detail - click physiotherapy
Close up animated photo of ACL tear in the knee.

ACL injury – the basics

For years we have assumed that if something is broken, we need to fix it. It makes sense to think this way, but this may not always be the case with an ACL injury.

An ACL injury occurs mostly with cutting sports, as the shin bone rotates outwards and the thigh rotates inwards. For more information on the exacts head over to our ACL injury page. For now, lets get to talking about operating.

Traditionally we have operated as soon as possible, to avoid any further giving way of the knee. Recent research highlights that with rehabilitation, some knees won’t give-way even without an ACL! But why would you want to avoid surgery?

ACL repairs are good, but they aren’t perfect. Our expectations of what we will be like after surgery are much higher than what reality leaves us with. Research demonstrates that only 42% of people receiving reconstructions will return to competitive sport. Also around half the people that have reconstructions will develop osteoarthritic changes within 10 years.

You also need to way up other complications like numbness post surgery. Or infection and other risks that come with having invasive surgery.

So, what’s the alternative?

Very simply, the alternative to ACL reconstruction, is not having ACL surgery and opting for knee rehabilitation. I understand this is a scary concept, but there is good evidence to say you are much better to at least give this option a go.

Why not have surgery?

We know from research, that there are people out there who cope without an ACL. We call these people ‘copers’. (yes, researchers aren’t the most creative bunch) The evidence in support of this is growing due to some good quality trials. The leading trial in this field is called the ‘CANON’ trial, by Frobell and his colleagues.

From this research it’s clear that around one quarter of total ACL injuries could cope without an ACL. This group of people were equally happy with the outcome of their knee. They had similar levels of discomfort, their return to sport rates were similar and most other measurable outcomes was the same.

Based on this research we can conclude that one quarter of people may not need an ACL reconstruction! These copers will respond well to knee rehabilitation and avoid the recovery after surgery as well as other possible complications like infection, joint stiffness and more.

What about further injury to my knee if it’s not repaired?

There is always a risk of further damage to knees regardless of surgery of not. The good news, is that there is no higher risk of injury if you choose to delay your ACL surgery. The risk of further meniscus damage is equal whether or not you get your ACL repaired. You don’t have to spend sleepless nights worrying about further damage to the knee any longer.

How can you tell if you’re a coper or not?

Time is the best answer to this question. When you sustain an ACL injury like this, it’s normal to want it fixed as quickly as possible. The evidence is now suggesting that you wait for a period and see how it goes.

Trial three months of rehabilitation and if the knee doesn’t give way, then you may succeed in avoiding surgery. Remember, even a year down the track there is always the option to continue with surgery – there’s no benefit for getting surgery early. You are not at risk of further injury!

What other things come into the equation?

It really matters what type of sport (if any) you want to get back to. People engaged in high intensity cutting sports like soccer or hockey would be encouraged to get the ACL surgery, even if they trialled three months knee rehabilitation with no giving way. This is because the demands placed on the knee during these sports are much higher.

If you aren’t interested in performing high-level, cutting sports, it’s totally fine to trial rehabilitation first and see how the knee responds.

Your opinion matters in this decision too. If you really want to have the surgery, it will probably be offered to you. Just remember to sum up the pros and cons, as many people have an unrealistic view of what their knee will be like after surgery.

What rehabilitation for ACL injury looks like

Whether you think you need surgery or not, all ACL deficient knees will need a period of knee rehabilitation. The purpose of this rehabilitation is to restore normal movement and restore strength and balance to the knee. Early on the rehabilitation will involve simple bending and straightening exercises to help the knee movement.

As the rehabilitation progresses your therapist will add more strength-based and balance exercises to help the knee recover. The balance exercises help the knee to identify where it is in space, without having the ACL ligament to relay some of that information. To find out more about progressing load effectively – check out our blog titled ‘what your rehabilitation is missing

The last aspect of rehabilitation is getting the knee ready for more high demand such as cutting, jumping and hopping. At any stage during this rehabilitation if the knee gives way or feels really unsteady, then surgery may be the option you need. Click Physiotherapy can help with your knee rehabilitation from start to finish, click here if you would like to book a free initial appointment.

Online rehabilitation is idea for ACL injuries as we can walk with you daily, making sure your exercises are a perfect fit for where you’re at. Find out more about online physiotherapy treatment with this blog – ‘In pain? 3 reasons why you should choose online physiotherapy‘.

Final comments on ACL injury:

Not everyone will need an ACL reconstruction. Although it still is a great choice for those intending on returning to high-level, cutting sports or if your knee continues to give-way. If you delay surgery, there is NO increased risk of damage to the knee, and outcomes of a delayed surgery will be similar. So, get started with your knee rehabilitation early and that may be all you need!

To book your free initial consultation with a physiotherapist – click here!


Richard B. Frobell, Ewa M. Roos, Harald P. Roos, Jonas Ranstam, L. Stefan Lohmander (2010) A Randomized Trial of Treatment for Acute Anterior Cruciate Ligament Tears. The New England Journal of Medicine. 363:331-42

Stephanie R. Filbay, Hege Grindem. (2019) Evidence-based recommendations for the management of anterior cruciate ligament (ACL) rupture, Best Practice & Research Clinical Rheumatology,

Wellsandt, E., Failla, M. J., Axe, M. J., & Snyder-Mackler, L. (2018). Does Anterior Cruciate Ligament Reconstruction Improve Functional and Radiographic Outcomes Over Nonoperative Management 5 Years After Injury? The American Journal of Sports Medicine, 46(9), 2103–2112.