Novel ACL Bracing Protocol: Can a torn ACL heal on its own or does it require surgical intervention

A couple of months ago I attended an APA lecture run by Dr Tom Cross, a renowned sport and exercise physician with over 25 years of experience. The premise of this lecture was to learn and understand more about his “novel bracing protocol” in the management of an acute ACL injury. Can a torn ACL really heal on its own or can it only be surgically repaired?

This blog will detail a summary of notes presented by Dr Tom Cross. Whilst this research is still in the works I believe it was a really interesting lecture and a topic which has sparked conversations in the physiotherapy world regarding the future of ACL rehabilitation.

The beginning of this lecture explored the common beliefs of ACL rehabilitation and the history and explanation of spontaneous healing. We were shown MRI results of patients during the acute stage/9 weeks/6 months/9 months, his earliest findings, exclusion criteria based upon failed and successful patients, the bracing protocol as it stands currently and his acute MRI classification system which breaks down the injury into a spectrum and subsequently expected healing outcomes.

Let us begin with the earliest justification for healing based upon what Dr Cross explains as the 3 Key Orthopaedic Principles:

1. The Histology of ligament
– Ligaments do in fact have the capacity to heal

2. The Synovial Envelope
– There is a rich blood supply from the branches of the middle genicular artery, which form a vascular synovial envelope around the ligament

3. Principle of Anatomical Reduction
– Reduce the injury
– Approximate the injured ACL tissues

For me, the biggest takeaway was the 3rd Principle known as anatomical reduction. The reduction allows the healing of tissues in a shortened position. Think of this idea as the same principle for how a mallet finger is treated with the use of a splint.

This idea of bracing is not new by any means; Dr Cross highlighted studies in Japan, the US and Switzerland that assessed the capacity of healing of the ACL in a brace. One Japanese study looked at fixed flexion of 20 degrees and one American/Swiss collaboration did not have any fixed degree of flexion. What these studies showed was that the ACL had the capacity to heal but with a sag.

Dr Cross found that no studies had explored fixed bracing of the knee >20 degrees post ACL injury, which posed a question to him and his colleagues about potential research in this field. They identified a few reasons to justify bracing; one of which we have discussed in the previous post about the idea of reduction. Through arthroscopic (MRI) images of the ACL, they were able to observe the ACL at varying degrees of flexion.

At 30 degrees of Knee Flexion: ACL Fibres are taut.

At 90 degrees of Knee Flexion: ACL Fibres are not taut

It was interesting to note that at 90 degrees of knee flexion the ACL is most approximated (24mm vs 30mm); a shorter gap distance would ideally allow fibres to join.

As with all research, it is important to have an exclusion criterion. These are often developed to adhere to protocols and in this research project, clearly developed in response to the earliest trials that were not as successful. Trial and error is everything with innovative research but typically at the detriment of the early candidates and patients. Down below are the absolute and relative contraindications for the ACL Healing Research Project, identified by Dr Tom Cross.

Absolute Contraindications:
– Displaced bucket handle meniscal tear
– Osteochondral loose body
– Past or present DVT
– Strong family history of thrombosis/thromboembolism
– Presenting 3 weeks or more after acute ACL injury

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

There were a few contraindications that I found to be most relevant as a practitioner. The first is a past or present DVT, where each candidate was assessed via a doppler ultrasound to rule out a DVT. Makes perfect sense. The timing of which patients entered the protocol was also something that changed over the course of its initiative. What they found through their research was that the longer a patient was not immobilised the more likely the ACL stumps were to involute (roll or curl up), which is not ideal.

Patients are rejected if they present to the clinic more than 3 weeks post-acute ACL injury, based upon expected poorer outcomes with the bracing protocol. I think it is also important to note that one of the absolute contraindications was any displaced meniscal tear or loose osteochondral body. Given that majority of ACL injuries are not isolated, this tends to rule out potential candidates with more extensive knee injuries.
Now to the more interesting component: the bracing protocol which includes the parameters and guidelines that clients adhere to throughout the first 12 weeks of rehab. What does it entail, what are the aims and what are restrictions with ROM of the brace. Here is a little snap shot down below:

It is important to note that at 12 weeks there is a follow up which a clinical examination of the knee and an MRI.

What I found interesting was through his teams journey they were able to streamline and come up with their own acute MRI classification system. Dr Cross explained the need for simplicity and this would help identify ACLs with more favourable prognosis. Acute MRIs were broken into three types, and described as either being displaced or non-displaced.
Type 1: No avulsion
Type 2: Partial femoral avulsion
Type 3: Complete femoral avulsion

A non-displaced ACL being one where the tissues sit within the intercondylar notch. Versus a displaced ACL where a percentage of tissue sits outside the intercondylar notch.

Non Displaced ACL Fibres

Displaced ACL Fibres

For example a Type 1 non-displaced injury would be classified as the gold standard, or “podium finish” in the words of Dr Tom Cross. Versus a Type 3 displaced injury which would be a participation award and one that would be described as severe and in need of surgical intervention.

With research still in the works it is exciting to see what the future holds for this novel bracing project and ACL rehabilitation. What was abundantly clear through listening to Dr Cross was that there is a spectrum of injury, some mild and some more severe. Spontaneous healing is possible based upon the extent of the injury and his teams research has shown that the ACL does in fact have the capacity to heal on its own and does not always require surgical intervention.

If you have any questions about the bracing project or have clients that you think may be suitable for it, reach out to the Stadium Clinic where Dr Tom Cross and his team are based. Their details are down below:

Jamie Cheok – BeFit Training Physio Coogee

Jamie Cheok – BeFit Training Physio Coogee

Jamie Cheok is a physiotherapist based in Coogee in the Eastern Suburbs of Sydney. Jamie has successfully treated musculoskeletal problems on the basis of a thorough assessment and diagnosis coupled with evidence-based rehabilitation programs tailored to the needs and goals of each individual. To book a consultation, click the link below.

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