Can a Torn ACL Heal Without Surgery? | GCKG
Can a Torn ACL Heal Without Surgery? The Cross Bracing Protocol Explained
Dr Adam Walker (PhD) — Director and Head of Rehabilitation, Gold Coast Knee Group
You have torn your ACL. Somewhere in the next few days, someone will tell you that you need surgery. Probably several someones.
And then, most likely on your phone at eleven at night, you will come across something about a brace. A protocol where people wear a knee brace bent at ninety degrees for three months and the ligament heals on its own.
From the outside it is impossible to tell whether that is a genuine breakthrough or wishful thinking. Which is a difficult position to be in, because if it is real, the window to act on it is measured in days.
This article is about what the Cross Bracing Protocol actually is, who it might suit, what the evidence does and does not show, and why the first week after your injury matters more than almost anything that happens afterwards.
One thing before we start. I have no affiliation with the team behind the Cross Bracing Protocol. I read the evidence, I talk to the people who know it best, and I pay attention to what I see in my own patients. That is the whole basis for what follows.
First, the three options you actually have
Most people with a fresh ACL injury believe they have one option, and that option is an operation. In Australia that belief is understandable — we reconstruct more ACLs than almost anywhere in the world.
There are three:
The Cross Bracing Protocol — bracing the knee to give the torn ligament a chance to heal on its own.
Rehabilitation alone, with surgery kept on the table as a later option.
Early surgical reconstruction.
This article covers the first. We have written separately about managing an ACL injury with rehabilitation alone and about what recovery after ACL reconstruction really involves. There is also an excellent independent decision aid built by researchers at the University of Melbourne at aclinjurytreatment.com, which is worth an hour of your time and is not selling you anything.
None of the three is automatically the right one. Which suits you depends on your MRI, your knee, your sport, your timeline, and what you are prepared to trade.
What is the Cross Bracing Protocol?
It was developed in Sydney in 2014 by the late Dr Mervyn Cross, an orthopaedic surgeon, and his son Dr Tom Cross, a sports physician.
The idea is straightforward. Bend the knee to ninety degrees and the ACL sits in its most shortened position, which brings the torn ends as close together as they can get. Hold them there and you give the ligament the best chance to knit back together. It is not far off putting a cast on a broken bone.
The reason this is surprising is that for decades we were taught the ACL simply does not heal. That belief has been challenged repeatedly over the last few years2.
The protocol gained international attention in 2023 with a paper in the British Journal of Sports Medicine. In the first published case series of 80 patients, more than 90% showed evidence of ACL healing on their follow-up MRI1. Over 650 patients have now completed the bracing protocol.
That number deserves a caveat immediately. A case series reports on a group of people who all received the same treatment. There is no comparison group — which means it cannot tell us what those same knees would have done without the brace, and we know some ACLs heal spontaneously anyway2. It is genuinely promising. It is not the same thing as proof, and anyone presenting it as proof is overselling it.
That is changing. Further randomised controlled trials comparing the bracing protocol against both surgical and non-surgical management are set to commence, led by the University of Melbourne. Those multi-centre studies could be a big step forward for how ACL injuries are managed — and we are in talks with the authors about becoming the Gold Coast hub.
What the protocol involves
Four weeks in a brace locked at ninety degrees.
The range of movement is then gradually opened up over the following four to eight weeks.
A repeat MRI at twelve weeks to see what the ligament has actually done.
There are six, eight and twelve-week versions, chosen according to the injury.
The first week decides whether this is even an option
This is the part almost nobody is told, and it is the reason this article exists.
After an ACL tears, the torn ends begin to involute — they draw back and change shape. That starts from around seven to ten days after the injury. By about three weeks at the absolute outside, the window has closed.
So whether you are eligible for cross bracing is not decided by how motivated you are, or how much you want to avoid an operation. It is decided largely by how quickly you get imaged and assessed.
If cross bracing is something you want considered, these are the things worth raising with your GP in the first few days:
Ask for an urgent X-ray and MRI. Not next month. This week.
Ask whether the MRI can include a “double-oblique” sequence. It shows the ACL tear far more clearly and it is not always ordered as standard.
Ask whether hands-on ligament testing can wait. Some of the tests used to check ACL integrity involve pulling on the knee. The concern is the same as moving a broken bone before it has been imaged.
Ask about the brace position. The standard approach for a lot of knee injuries is a brace that holds the leg straight, which is the opposite of what cross bracing needs. If bracing is being considered it is worth flagging early.
Ask about crutches, to reduce the chance of doing more damage before anyone has looked at the scan.
Ask before you take anti-inflammatories. They are generally avoided in this window because of their potential effect on healing — worth a conversation rather than reaching for whatever is in the cupboard.
If that window is missed, cross bracing is off the table. Not because it was tried and failed — because it was never offered. That is the part that frustrates me most, and it is entirely avoidable.
Who the Cross Bracing Protocol suits
An ACL injury is now understood as a spectrum rather than a single thing, in the same way most injuries are. Dr Tom Cross describes three broad groups:
Minimally injured — rehabilitation alone, or a shortened six-week bracing protocol alongside rehabilitation.
Moderately injured — an eight or twelve-week bracing protocol alongside rehabilitation.
Severely injured — referral to an expert knee surgeon to consider reconstruction, or rehabilitation alone.
Where your MRI places you comes down to a few things:
Where the tear is. Tears closer to the top of the ligament are more likely to heal.
The gap between the torn ends. The bigger the gap, the lower the chance.
How long it has been. Covered above, and it is the one you have any control over.
Who makes that call is not you, and it is not your physiotherapist either. It is a sports and exercise medicine physician with specific training in the protocol, reading your scan. On the Gold Coast we work closely with Dr Luke Eggleston and the team at SEQSEM, who have collaborated with Dr Tom Cross in Sydney. Interest among knee surgeons on the coast has been growing.
We have referred plenty of people for assessment who were then ruled out — either because of the type of tear, or because the diagnosis took too long. That is a normal outcome rather than a failure, and it is far better to be ruled out having asked than to never have asked.
What twelve weeks in a brace is actually like
The team behind the protocol give patients a clear list of pros and cons before anyone commits. Here are the ones that matter most.
The case for it
The possibility of your own ACL healing — a ligament of normal thickness and tension at nine to twelve months, rather than a graft taken from somewhere else in your leg.
Avoiding the risks that come with any operation: pain, infection, bleeding, blood clots, anaesthetic and surgical scars.
Avoiding graft site problems, such as pain at the front of the knee or hamstring weakness.
Considerably less pain and discomfort, particularly in the first two to three weeks.
Lower cost.
Surgery is still available later if it does not work out.
The case against it
Twelve weeks in a brace. The first four to six are the hard part, and there is no pretending otherwise.
You may not be able to drive for a period if it is your right knee.
Risk of a blood clot, which is why the protocol includes blood-thinning medication, specific exercises and compression garments.
The ligament may heal in a lengthened position with a sag, or fail to heal at all.
Muscle wasting from prolonged immobilisation.
Joint stiffness from prolonged immobilisation.
If healing is sub-optimal, add roughly three months to your return-to-sport timeline.
We do not yet have good five to ten year follow-up data on large numbers of people.
That is a lot to weigh up, which is exactly why the triage matters and why the physiotherapy alongside it matters. The clot risk, the stiffness and the muscle loss are all things that get actively managed rather than simply accepted.
In my experience, patients handle the bracing period better than they expect to, and the list of downsides is not enormously different from the one that comes with surgery. You come out of the brace stiff and weak — but that responds well to a decent rehabilitation program. There are also some genuinely useful online support groups full of people who are a few weeks ahead of you and have worked out the practical tricks.
What the outcomes look like
Following the bracing protocol, patients can return to sport in roughly the same timeframe as they would after a reconstruction.
On the repeat MRI at around nine to twelve months, a healed ACL can closely resemble a normal one. The scans are graded on the signal within the ligament, how taut it is and how thick it is. Early data suggests that ligaments achieving a higher healing grade — the ones that look most like a normal ACL — tend to have better functional outcomes.
I have rehabilitated several people back to high-level sport — including professional skateboarding, soccer and surfing — following complete, gold standard healing of the ACL. They have been very happy with the decision they made.
The reinjury rate appears comparable to reconstruction.
One thing that gets lost in the excitement about healing: rehabilitation is not optional here. It runs throughout the bracing period and all the way through the return-to-sport process. A healed ligament sitting in a leg that has lost three months of strength is not a knee you can play sport on. The ligament is one part of the job.
The bottom line
The evidence behind cross bracing is still limited, and we should stay balanced rather than being swept along by the newest and most interesting thing. That applies to me as much as anyone.
In saying that — it is an exciting area with real promise, and the early results are hard to ignore.
If I tore my ACL tomorrow and my MRI said I was eligible, I would use the Cross Bracing Protocol. That is a personal view about my own knee, not a recommendation for yours.
Because here is the thing. The decision that actually matters this week is not which of the three treatments you choose. It is getting assessed quickly enough that all three are still open to you. Miss that, and the choice gets made for you by a calendar.
Torn your ACL in the last week or two?
Time matters more than anything else right now. Our Sports Knee Program is built for people working through exactly this decision, and we can help you get the right imaging and the right assessment quickly enough that all three options stay open. If you are not sure where to start, an initial knee consultation is the place.
We see patients across the Gold Coast at Robina, Currumbin and Benowa. You can get in touch with our team or phone 0408 051 943.
Frequently asked questions about ACL healing and the Cross Bracing Protocol
Can a torn ACL really heal on its own?
It can, in some cases. For decades the accepted view was that it could not, and that view has been challenged by a number of publications over recent years. The Cross Bracing Protocol is built on the idea that holding the knee at ninety degrees brings the torn ends close enough together to give healing the best chance.
In the first published case series of 80 patients, more than 90% showed evidence of healing on MRI. That is a promising signal from a study design that cannot prove cause and effect, so it should be read as encouraging rather than settled.
How long do I have to decide?
Far less time than most people realise. The torn ends of the ACL start to involute from around seven to ten days after the injury, and by roughly three weeks the opportunity has generally gone.
Practically, that means the MRI and the specialist assessment need to happen inside the first week or so. If you are reading this within a few days of injuring your knee, that is the single most useful thing to act on today.
Am I eligible for cross bracing?
That is decided by a sports and exercise medicine physician with training in the protocol, reading your MRI. The main factors are where the tear sits in the ligament, how big the gap is between the torn ends, and how long it has been since the injury.
Plenty of people are assessed and ruled out. That is a normal result, and knowing early lets you get on with choosing between the other two options.
What happens if the ACL does not heal?
You still have the same options you started with. The ligament may heal in a lengthened position with a sag, or not heal at all — both are on the list of known downsides. If that happens, surgical reconstruction remains available, or a period of rehabilitation alone.
The main cost of an unsuccessful attempt is time. Where healing is sub-optimal, expect roughly an extra three months before returning to sport.
Can I still have surgery later if I try bracing first?
Yes. Delayed reconstruction remains an option throughout, and that is one of the reasons the protocol is worth considering for people who are eligible.
Do I still need physiotherapy while I am in the brace?
Yes, and this is the part people underestimate. Rehabilitation runs throughout the bracing period and continues right through the return-to-sport process.
Three months of immobilisation costs you muscle and movement. Getting the ligament to heal and then discovering the leg cannot do anything is not a good outcome, and it is avoidable with a decent program alongside.
Is there a risk of a blood clot?
Yes, and it is taken seriously. Prolonged immobilisation raises the risk of deep vein thrombosis, which is why the protocol includes blood-thinning medication, specific exercises and compression garments as standard rather than as optional extras.
It is one of several reasons this is not something to attempt without proper medical supervision.
Will I be able to drive?
If it is your right knee, likely not for a period. It is worth planning around before you commit, particularly if you drive for work or have school runs to manage.
How does the return-to-sport timeline compare with surgery?
For people whose ligament heals well, return to sport happens in roughly the same timeframe as after a reconstruction. Where healing is sub-optimal, add around three months.
In both cases the timeline is driven far more by the quality of your rehabilitation than by which treatment you chose.
Is the Cross Bracing Protocol proven?
Not in the way that word is usually meant. What exists is a promising early case series, a growing body of work challenging the old assumption that ACLs cannot heal, and clinical experience that has been broadly positive.
What does not yet exist is long-term follow-up on large numbers of people. That is a fair reason for caution, and it is why the decision is worth making with someone who knows the evidence rather than on the strength of a social media post.
References
1 Filbay SR, Dowsett M, Chaker Jomaa M, et al. Healing of acute anterior cruciate ligament rupture on MRI and outcomes following non-surgical management with the Cross Bracing Protocol. British Journal of Sports Medicine 2023;57:1490-1497.
2 Filbay S, Roemer F, Lohmander S, Turkiewicz A, Roos EM, Frobell R, Englund M. Spontaneous healing of the ruptured anterior cruciate ligament: observations from the KANON trial. Osteoarthritis and Cartilage 2022;30:S21-S22.
