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An ACL rupture is a significant injury in both professional and recreational sports. Research suggests that up to 25% of people may not return to their previous level of sport, and many can be disappointed in their long-term knee function after having this injury.
How is the ACL injured?
The injury usually occurs as a result of pivoting on a fixed foot or landing from a jump, and the knee buckling inwards. This causes tensioning of the ligament, and it subsequently fails. The classic signs of an ACL rupture are feeling a “pop” or crack in the knee and a feeling of it dislocating. The knee usually swells within a few hours and will feel stiff and potentially unstable.
What are the treatment options?
Traditionally, after rupturing your ACL, there are generally 2 options for you: ACL reconstructive surgery or non-surgical rehabilitation to strengthen the thigh muscles to support the ACL-deficient knee.
However, there is now further conservative options, including the “Cross Bracing Protocol”. This novel approach allows you to heal your own ACL without the need for reconstructive surgery and can potentially restore the ACL to 90-95% of the strength of the uninjured knee.
What is the back story?
Common myths were that the ACL had “no capacity to heal” and that having ACL reconstructive surgery would help prevent knee osteoarthritis caused by having an unstable knee.
What we have since discovered is that the ACL can in fact, heal on its own. We know that up to 1/3 of ACL injuries that do not go on and have surgery will heal without any intervention at all. Due to this, more people are now exploring ways to enhance the ACL’s capacity to heal by itself, just like other ligaments and tendons around the human body that are already being managed conservatively.
There are now many longitudinal studies showing that ACL surgery does not reduce the likelihood of developing knee osteoarthritis either. In fact, some research shows an increased prevalence of osteoarthritis in knees that have previously undergone surgical reconstruction. It may be that the traumatic injury of ACL rupture was the initial precursor to future deterioration to the joint but this research is ongoing.
Around 10 years ago, a bracing approach was first developed by 2 doctors in Australia. Dr Tom Cross and his father, Dr Mervin Cross. They were bold enough to experiment with this bracing technique on a close acquaintance who did not want surgery but was passionate to return to sport with as stable a knee as possible. Dr Mervin Cross, an orthopaedic surgeon specialising in reconstructing the ACL, initially proposed the idea to his son, Dr Tom Cross, based on an old-fashioned technique used back in the 1970s. Over a 6-year period, they slowly developed and enhanced the bracing protocol on a small number of patients before rolling it out on a much larger scale, and subsequent research projects followed. There have now been thousands of patients treated with the “Cross Bracing Protocol” by Dr Tom Cross and his research group.
A recent study in 2023 showed a 90% success rate with healing the ACL using the Cross Bracing Protocol.
It is important to note that not all ACL injuries can be managed using this bracing protocol, and surgery can still be the best option for many patients. It is important to get expert advice to see if you are the right candidate to try it. The key to having a successful outcome with bracing is getting an early diagnosis and starting the bracing protocol early- ideally within the first 4-10 days post injury. If you are more than 3 weeks since your ACL injury, your chance of having a successful conservative outcome dramatically reduces. The findings of the MRI scan will also dictate whether you are the right candidate, as some findings will exclude you for example, if the ACL is too severely damaged or there is a large meniscal tear in the way of the healing ACL.
What does it involve?
In a nutshell, you will have a brace on your knee locking it at 90 degrees 24 hours a day for the first few weeks in the brace. Then it will be gradually unlocked over the subsequent weeks to allow more range of motion at the knee but it will still be challenging to mobilise around without mobility aids like crutches and kneeling scooters.
There are a few variations on the original 12-week protocol, but the original protocol is as follows:
There are now 6 and 8-week versions and a hybrid for those not able to be completely locked at 90 degrees 24 hours a day.
The decision on what protocol to follow will be based on your own circumstances, the severity of the injury and your specialist’s advice.
What can I do while braced?
While you are following the Cross Bracing Protocol, you will need to maintain the strength of your leg by having regular Physiotherapy. You will have a range of exercises to perform at the gym and at home. You can still be very active after the first 2 weeks, as we want you to maintain your fitness and be as strong as possible as you mobilise out of the brace. Swimming with a brace on is fine, spending time out of the brace to wash is also fine, as well as resting with no brace on if you can maintain the knee in the right position. You will always need to sleep in the brace while you are restricted at certain angles.
Ideally, you should also have a muscle stimulator to keep the quadriceps active while braced.
Essentially, any exercise you can tolerate will be fine as long as you are still locked in the brace (with the exception of high-impact and twisting sports, obviously!). Ski erg, hand cycle, seated boxing, and swimming are all ways of maintaining cardiovascular fitness too.
Are there any downsides?
Some people may need to drive, and that will not be possible if the foot you use to drive a car has the knee locked at 90 degrees.
There is a risk of deep vein thrombosis (DVT), which can happen when you don’t move a limb for a period of time. This is mitigated by taking a blood-thinning tablet that your specialist will prescribe.
It may not work. Some ligaments may not be in the best shape to knit back together, so a follow-up MRI will inform us if this is the case and then other interventions can be considered.
It is hard work being on crutches for such a long period, and mentally challenging, not knowing something isn’t ‘fixed’ straight away.
You may develop pain around the knee cap from the knee being held in a bent position for such a long period. This should ease with Physiotherapy and straightening of the knee.
What are the upsides of the Cross Bracing Protocol?
Avoiding surgery. Surgery usually requires 6 weeks of strengthening to build up to the procedure, and with all surgeries, there is discomfort. You will have a scar on the front of the knee, and you are on crutches for a minimum of a week post-op op and then you need to rebuild your strength and range of motion up again. You will build up to potentially return to running 4 months after surgery. Return to sport at 12 months.
You will also not have to give up part of your hamstring tendon or patellar tendon for the ACL graft, leaving another area of the body slightly weakened.
The cost if you are self-paying, will be significantly less than surgery as the majority of the work to repair the tissue is done by you. You will, however, need a fixed-angle hinged knee brace, crutches and 3 MRI scans – one to diagnose the severity of the injury, a second at 12 weeks to see if it is working and a final scan at 12 months to discharge you back to sport. You will also need to be under the care of a sports medicine doctor / Orthopaedic consultant and a Physiotherapist.
How do we know if it has worked?
It is important to have an MRI scan after 12 weeks to see if the ligament is showing signs of healing. You will be out of the brace at this point, and it allows us to make an informed decision about the best next steps in your rehabilitation.
Below is an MRI of one of our patients, day 1 post injury and 12 weeks later, after following the Cross Bracing Protocol under our care: You can see the dramatic improvement in the ligament structure in just 12 weeks!
Normal ACL
Acute ACL injury day 1 – Note the wavy appearance of the ACL due to rupture.
This is the same patient’s knee 12 weeks later….
Note the now-healing ACL with the ligament now with parallel fibres connecting the bones!
When can I return to sport?
After 12 weeks, your ligament will hopefully have significant signs of repair and should be around 50% strength of the uninjured leg. Unfortunately, that is still not strong enough to play sports. Achieving full maturation of the ligament will take about 12 months. The re-rupture rate is around 15% after this point, which is similar to surgical outcomes, and time frames are very similar with either approach.
What are the key points to consider?
- Are you under 3 weeks since the injury?
- Do you want to avoid surgery if possible?
- Are there any reasons why you can’t be braced for a period of time while the ligament heals?
The Cross Bracing Protocol can dramatically enhance your body’s own healing potential of the ACL. So if you want to try this approach, it is important to get in touch as soon as possible so we can brace you within the ideal window. If there is no satisfactory healing at 12 weeks, you can always revert back to a surgical repair or rehabilitation alone. We will need to liaise with an Orthopaedic surgeon, and possibly a Sports medicine doctor and a radiologist, to ensure you can make an informed decision before proceeding.
Please do get in touch if you wish to find out more. Below is a patient information booklet about the Cross Bracing Protocol process.