The recently published Cross Bracing Protocol is a bracing regime designed to maximise the healing ability of the ACL by keeping the knee bent at 90 degrees for four weeks post-ACL injury before releasing it slowly into a more straightened position. It works on the hypothesis that at 90 degrees, the ACL is in the ideal healing position and that after an ACL rupture, there is a ‘healing window’ that closes at about 14-20 days post-injury. The first publication in the British Journal of Sports Medicine is a ‘case series’ outlining the results of the first 80 people who have undergone the protocol (currently up to over 400 participants and counting). The healing rates published in the first study are 90% (72 out of 80). A recent review of the excellent KANON study on ACL management showed healing rates of 30% in people who did no bracing at all.

The founder of the study, Tom Cross, is a renowned Sports Doctor from Sydney, and his father, Merv Cross was the first person to perform ACL reconstruction in Australia after learning the technique in the USA in the 1980s. Note that the term ‘Cross-bracing’ refers to the founders’ names, not the shape of a cross.

The Case Against
It’s important to note that this paper is a ‘case series’ rather than a randomised control trial, so there was no group of people to compare the results with directly. And a double-blinded control group, who were not aware if they were having the treatment, is unlikely to be possible with this protocol. This means the evidence is of lower quality than the gold-standard double-blinded RCT. The CBP requires taking anti-coagulant medication to lower the risk of deep vein thrombosis (DVT), and some people cannot take these medications. Concerns have been raised regarding the post-bracing stiffness in the knee, weakness in the muscles and possible degeneration of cartilage due to the immobilisation and non-weight-bearing period. The practicality of living for 4-6 weeks with a knee bent at 90 degrees is also a concern. This protocol is unlikely to be helpful for more severe knee injuries involving other structures requiring surgical repair.

As with all research, it is crucial to have an exclusion criterion. Below are the absolute and relative contraindications identified by the authors.

Absolute Contraindications:
– Displaced bucket-handle meniscal tear
– Osteochondral loose body (chip of bone that has come away from the knee)
– Past or present history of DVT
– Strong family history of thrombosis/thromboembolism
– Presenting three weeks or more after acute ACL injury

Relative Contraindications:
– Medical conditions
– Mobility
– Social support
– Right knee and driving

What Does This Mean For ACL Management in the Future?
The confirmation of the ACL’s healing ability, coupled with recent findings that ACL reconstruction does not reduce meniscus tears, prevent osteoarthritis or increase the chance of returning to pivoting sports, seems everything is now up for grabs. This study has received mainstream media attention, with Washington Post and Sydney Morning Herald articles. Many in the industry still do not believe an ACL can fully heal and are concerned about the abovementioned adverse effects. This protocol is also clearly not for everyone. Professional athletes are unlikely to be satisfied with the extra time off sports and loss of function. Older people with more modest future sporting goals may not see the inconvenience of the bracing protocol to be worth it. People who need to drive or work in physically demanding jobs may decide the protocol is not for them.

ACL Grading
Another breakthrough from this study and area for future research is to use an early MRI to identify what types of tears are more likely to heal and be suitable for the protocol as well as excluding tears that have lower healing ability – i.e. tears in which the whole ligament has pulled from the bone (avulsions) and tears where the stumps have reflected and rolled back. The researchers have developed a new grading system in tears, in which expert musculoskeletal radiologists are needed to provide their input in the management and likelihood of healing.

What to Do if You Rupture Your ACL?
It is becoming more complicated! It is paramount that every case should be treated individually; there is no one-size-fits-all approach to ACL injury management. Also of great importance is to seek out healthcare professionals who have extensive experience managing ACL injuries and are current with recent evidence; most are not.

Time is of the essence! See a sports doctor or orthopaedic surgeon interested in knees and ACLs who can assess you and refer you for an MRI to be read by an expert musculoskeletal radiologist interested in the ACL. The CBP authors recommend avoiding anti-inflammatory medication and having fluid drained from the knee as the body’s natural healing response likely creates an ideal healing environment for the ACL.

Keep the knee bent (do not actively push it straight), and try to minimise weight-bearing until the diagnosis and treatment pathway are confirmed.

See a physiotherapist with experience in ACL healing and early-stage ACL management and get fitted with a knee brace, possibly crutches, and other products to protect and provide pain relief for the knee. Work with your physiotherapist on exercises to keep the muscles working and prevent wastage and stiffness. Use a shared decision-making model to decide the best course of treatment. If you choose the Cross Bracing Protocol, it requires a multi-disciplinary approach with input from a doctor, radiologist and physiotherapist.

Check out our podcast, The Knee Gurus, with various episodes targeted to people with ACL injuries trying to decide on management.

Non displaced ACL fibres

If you have any questions about the bracing project or have clients that you think may be suitable for it, please reach out to us.