The History of the Cross Bracing Protocol

The Cross Bracing Protocol has a very long history, stretching back 50 years to when Dr Mervyn Cross was looking at the anatomy of the ACL in Columbus Georgia in 1973. This work at the famous Hughston Clinic led to a landmark paper on the anatomy of the ACL and more importantly gave Dr Cross an even deeper understanding of the ACL’s function and anatomy.

This understanding translated to clinical practice as Dr Cross reconstructed the ACL in patients who had ruptured the ligament. Initially the knee was kept at 90 degrees after surgery, a position protective to the ACL as it is at this flexion angle that the ACL is under the least stress. When superior ACL reconstruction graft and fixation methods were adopted this 90-degree approach was abandoned in favour of earlier mobilisation and rehabilitation.

Over the intervening years sporadic reports of spontaneous healing of the ACL occurred but were not common and it remained a mystery. Surgical reconstruction became commonplace and new techniques were developed including arthroscopic assisted reconstruction, greatly reducing the trauma of the previously open ACL surgery for the patients. Across the world different protocols, including a trial of rehabilitation alone, were developed, adopted and some were abandoned. Surgical ACL reconstruction remained the gold standard.

Then fate intervened. Dr Mervyn Cross was at the Stadium Clinic rehabilitating from bilateral knee replacements in 2014. Emma Rodger, a 19-year-old netball player was also at the Stadium Clinic consulting Dr Tom Cross with a recently ruptured ACL. Emma was in floods of tears as she absolutely did not want surgery. Emma was the daughter one of the Stadium Clinic reception team, Julie Rodger. Dr Tom Cross involved his father Merv in the consultation with Emma. Dr Mervyn Cross consoled Emma and, casting his mind back more than four decades, suggested bracing at 90 degrees and immobilising the knee at this angle for 4-weeks to see if it might heal. It was a long shot. The ACL healed. This proved nothing however and was seen as a fortunate outlier.

Over the next five years from 2014-2018 four similar cases presented themselves and were managed by Dr Tom Cross and Dr Merv Cross together and slowly the “Cross Bracing Protocol” was developed. All 4 patients healed. We now know this was fortunate, as there had been no MRI based selection of appropriate injury patterns, but the results were sufficient to encourage a tentative step towards adopting the Protocol for more patients.

Simultaneously the interpretation of the MRI scans at Dr Tom Cross’ practice was studied and became more refined and attuned to indicating, and finally classifying, the location and extent of the injury to the ACL. This was pivotal.

Then Dr Tom Cross and his MSK specialist Radiologist co-authors realised that there was a spectrum of injury to the ACL seen on the acute MRI and that this spectrum was closely associated on the chance of healing. This spectrum of injury now finally explained the poorly understood enigmatic “spontaneous healing”. Follow-up MRI at 12-weeks showed a “spectrum of ACL healing” shining the light on,

1. Spontaneously healed ACLs were the less injured ACLs
2. The Cross Bracing Protocol is significantly associated with “facilitated healing” of the ruptured ACL. Instead of the ACL being left to fend for itself, it is held at 90 degrees flexion of the knee, bringing its ends closer together and allowing it to heal – that was insight that drove the commencement of the first trial, the research now published in the BJSM.

After presenting the very early results of the first 16-patients at a 2020 Sports Medicine Conference in Australia, Dr Tom Cross realised he needed help to pursue the compelling notion of potentially facilitating the healing of the ruptured ACL. Eminent Melbourne based clinical Physiotherapist Jane Rooney introduced Dr Cross to Dr Stephanie Filbay, an academic research physiotherapist based at the University of Melbourne.

Dr Filbay had recently published the KANON Trial, a pioneering publication discussing spontaneous ACL healing in patients treated with rehabilitation alone and comparing these patients with those patients who were randomised to ACL reconstructive surgery. Dr Filbay was across all relevant academic literature and in particular research relating to ACL injury. Dr Tom Cross assembled a team of clinicians and researchers, the co-authors of the BJSM publication, to work together to determine whether ACL healing could be proven to be facilitated by the Cross Bracing Protocol.

Much was learned in the management of the first 80 patients, lessons that have been applied to hundreds of Dr Tom Cross’ patients since and which form the now published and refined Cross Bracing Protocol. The vast majority of these lessons have been acquired during the hands-on management of patients by Dr Tom Cross and his team of physiotherapists, other Sports Medicine Doctors adopting the protocol, and the insights from Radiologists interpreting the MRI images. It has been a team effort!

Confidence in the Cross Bracing Protocol has grown, understanding of which patients are suitable based on the MRI and which are not is far greater, and the means of adopting the protocol with the least inconvenience and discomfort to patients is better applied. But there remain grey areas of patient selection that will be illuminated with time, more advanced MRI imaging, more patients adopting the CBP, and with open minded assessment of the data as it comes to hand.

There will be more research papers, modifications of the Protocol for subsets of patients and, most importantly, the gathering of long-term data on the outcomes of the knees treated with the Cross Bracing Protocol. The most intriguing questions being the survivorship of the healed ACLs and the incidence of premature osteoarthritis 10-15 years after the CBP was adopted and then comparing both aspects to what is known regarding their incidence following ACL reconstructive surgery.

The Cross Bracing Protocol research is hypothesised to explain the previously enigmatic “spontaneous healing” of the ACL seen in the KANON Trial and other publications on this subject: That the “spectrum of injury” to the ACL explains the phenomenon of spontaneous healing.

These extensions from the early anatomic studies by Dr Mervyn Cross in 1973 and the dramatic insight of a “spectrum of Injury” by Dr Tom Cross, will, we believe, contribute to significantly better outcomes for patients afflicted with an ACL rupture.

Timeline:

1973 – Dr Mervyn Cross does anatomic studies on the knees of cadavers.

1979 – The American Journal of Sports Medicine publishes the results of these studies. “Anterior cruciate ligament: Functional anatomy of its bundles in rotatory instabilities.” LA Norwood , MJ Cross. Am Journal Sports Med 1979 Jan-_Feb.

1974-2012 Dr Mervyn Cross reconstructs thousands of Anterior Cruciate Ligaments, assisted in the final 15 years by his son Dr Tom Cross.

2014 – Patient #1 is braced at 90 degrees for 4 weeks, then gradually brought out straight over the next 4 weeks.

2014-2019: 6 patients adopt the early “Cross Bracing Protocol”.

Feb 2020 – Dr Tom Cross presents these early results of 16 patients who adopted the CBP at the Australian Sports Medicine Conference in Canberra.

March 2020 – Dr Tom Cross is introduced to Dr Stephanie Filbay of the UoM by Jane Rooney.

2021 – Dr Mervyn Cross presents the Cross Bracing Protocol at the international meeting of the Herodicus Society, an invitation only international specialist knee surgery group, in the US.

2020 –2023 Dr Tom Cross, his team, and Dr Filbay agree to collaborate in the writing up and submission for publication to the BJSM of the results of the first 80 patients to adopt the Cross Bracing Protocol.

2014-2023: Over 460 patients are enrolled in Dr Cross’ research and continue to be treated with this novel Cross bracing technique with the longer-term results being followed up for years to come.

June 2023 – Publication of the first 80 patients in the British Journal of Sports Medicine.

2023 into the future: ongoing clinical implementation of the Cross Bracing Protocol, relentless research and many more publications of the findings that we anticipate will further the understanding of ACL injury and hopefully lead to better outcomes for patients.