The anterior cruciate ligament (ACL) is an important ligament in the knee. It runs from the thigh bone (femur) to the shin bone (tibia) and helps stabilise the knee joint.

Injuries to the ACL, often called a “tear” or a “rupture”, are common in sport. While a ruptured ACL has just sidelined another Matildas star, people who play sport recreationally are also at risk of this injury.

For decades, surgical repair of an ACL injury, called a reconstruction, has been the primary treatment in Australia. In fact, Australia has among the highest rates of ACL surgery in the world. Reports indicate 90% of people who rupture their ACL go under the knife.

Although surgery is common – around one million are performed worldwide each year – and seems to be the default treatment for ACL injuries in Australia, it may not be required for everyone.

What does the research say?

We know ACL ruptures can be treated using reconstructive surgery, but research continues to suggest they can also be treated with rehabilitation alone for many people.

Almost 15 years ago a randomised clinical trial published in the New England Journal of Medicine compared early surgery to rehabilitation with the option of delayed surgery in young active adults with an ACL injury. Over half of people in the rehabilitation group did not end up having surgery. After five years, knee function did not differ between treatment groups.

The findings of this initial trial have been supported by more research since. A review of three trials published in 2022 found delaying surgery and trialling rehabilitation leads to similar outcomes to early surgery.

A 2023 study followed up patients who received rehabilitation without surgery. It showed one in three had evidence of ACL healing on an MRI after two years. There was also evidence of improved knee-related quality of life in those with signs of ACL healing compared to those whose ACL did not show signs of healing.

Regardless of treatment choice the rehabilitation process following ACL rupture is lengthy. It usually involves a minimum of nine months of progressive rehabilitation performed a few days per week. The length of time for rehabilitation may be slightly shorter in those not undergoing surgery, but more research is needed in this area.

Rehabilitation starts with a physiotherapist overseeing simple exercises right through to resistance exercises and dynamic movements such as jumping, hopping and agility drills.

A person can start rehabilitation with the option of having surgery later if the knee remains unstable. A common sign of instability is the knee giving way when changing direction while running or playing sports.

To rehab and wait, or to go straight under the knife?

There are a number of reasons patients and clinicians may opt for early surgical reconstruction.

For elite athletes, a key consideration is returning to sport as soon as possible. As surgery is a well established method, athletes (such as Matilda Sam Kerr) often opt for early surgical reconstruction as this gives them a more predictable timeline for recovery.

At the same time, there are risks to consider when rushing back to sport after ACL reconstruction. Re-injury of the ACL is very common. For every month return to sport is delayed until nine months after ACL reconstruction, the rate of knee re-injury is reduced by 51%.

Historically, another reason for having early surgical reconstruction was to reduce the risk of future knee osteoarthritis, which increases following an ACL injury. But a review showed ACL reconstruction doesn’t reduce the risk of knee osteoarthritis in the long term compared with non-surgical treatment.

That said, there’s a need for more high-quality, long-term studies to give us a better understanding of how knee osteoarthritis risk is influenced by different treatments.

Rehab may not be the only non-surgical option

Last year, a study looking at 80 people fitted with a specialised knee brace for 12 weeks found 90% had evidence of ACL healing on their follow-up MRI.

People with more ACL healing on the three-month MRI reported better outcomes at 12 months, including higher rates of returning to their pre-injury level of sport and better knee function. Although promising, we now need comparative research to evaluate whether this method can achieve similar results to surgery.

What to do if you rupture your ACL

First, it’s important to seek a comprehensive medical assessment from either a sports physiotherapist, sports physician or orthopaedic surgeon. ACL injuries can also have associated injuries to surrounding ligaments and cartilage which may influence treatment decisions.

In terms of treatment, discuss with your clinician the pros and cons of management options and whether surgery is necessary. Often, patients don’t know not having surgery is an option.

Surgery appears to be necessary for some people to achieve a stable knee. But it may not be necessary in every case, so many patients may wish to try rehabilitation in the first instance where appropriate.

As always, prevention is key. Research has shown more than half of ACL injuries can be prevented by incorporating prevention strategies. This involves performing specific exercises to strengthen muscles in the legs, and improve movement control and landing technique.

Anthony Nasser, Senior Lecturer in Physiotherapy, University of Technology Sydney; Joshua Pate, Senior Lecturer in Physiotherapy, University of Technology Sydney, and Peter Stubbs, Senior Lecturer in Physiotherapy, University of Technology Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The United States Centers for Disease Control and Prevention (CDC) has revised its long-standing guidance about vaccines and autism.

The guidance once stated clearly and correctly that the evidence shows no link between vaccines and the development of autism.

Now it claims “studies supporting a link [between vaccines and autism] have been ignored by health authorities”. It also says:

The claim “vaccines do not cause autism” is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.

Health Secretary Robert F. Kennedy Jr directed the CDC to make these changes, despite promising at his confirmation not to alter the CDC’s vaccine advice.

With this change in wording on the website the CDC has been dragged to a new low. The CDC once stood as a global benchmark of scientific integrity. Sadly, it now risks becoming a megaphone for misinformation and a tool for those whose goal is to undermine science.

Let’s look at the updated CDC statement about vaccines and autism, and how this is at odds with how science works.

Science can’t prove universal negatives

Saying “studies have not ruled out the possibility that infant vaccines cause autism” is in direct conflict with how science works.

Using science, we can demonstrate that two things are linked by showing consistent, reproducible associations that stand up across multiple study designs. We can also test a hypothesis repeatedly and from many angles.

Therefore, for example, when high-quality studies using different methods, populations and measurements, all fail to find a link between vaccines and autism, the rational conclusion is there is no causal connection.

But we cannot prove the universal absence of a link.

If we were to accept this notion, someone could always claim they aren’t convinced by the current evidence because maybe the next study will find something. Using this same logic, it’s impossible to rule out the Earth is flat or that fairies exist.

It’s wrong to reverse the burden of proof

Another dangerous premise in the CDC’s new framing on vaccines and autism is it reverses the burden of proof.

In science, the person making a claim, especially one that argues against the available consensus, must provide the evidence for it.

The rhetorical manoeuvre on the CDC website suggesting proof is required to show the absence of a link, however, flips this principle on its head. It suggests it’s reasonable to expect scientists to defend against an infinite list of hypothetical possibilities.

But as US astronomer Carl Sagan famously put it, “extraordinary claims require extraordinary evidence”. In science, if you want to assert something that contradicts the scientific consensus, the burden is on you to produce evidence strong enough to justify overturning what we already know.

The more implausible a claim is, the higher the bar in providing high quality, reproducible and methodologically sound research to support it.

By asking the CDC to alter its website guidance, RFK Jr wants you to accept the opposite: that he or anyone can make any claim and it’s the responsibility of everyone else to disprove these claims.

It’s also unclear what evidence would change RFK Jr’s mind on vaccines and autism. This leaves the door open for him to claim any amount of evidence that doesn’t support his preferred narrative is insufficient.

But what about the study that claimed to be proof?

Speculation about a link between the measles, mumps and rubella (MMR) vaccine and autism began with a fraudulent and now-retracted 1998 Lancet paper by the discredited doctor Andrew Wakefield.

Even if you accepted everything in Wakefield’s paper as true (it wasn’t) and assumed he was an honest researcher (he wasn’t), you would still be left with nothing more than a case series of 12 children. This study design is incapable of establishing a causal link between the MMR vaccine and autism.

Subsequent investigations also uncovered a long list of damning findings about Wakefield, including:

1) He hid major financial conflicts of interest

Wakefield was paid large sums by lawyers preparing a lawsuit against MMR manufacturers, money he failed to disclose. He was contracted to find evidence supporting a link between MMR and autism.

At the same time, he had filed patents for a single-dose measles vaccine and a diagnostic test that stood to profit if public fear about MMR increased.

2) He committed serious ethical violations

Wakefield falsely claimed the study had ethics approval. It did not. Children with developmental conditions were subjected to invasive procedures, including colonoscopies and lumbar punctures, without valid clinical justification or proper oversight.

3) He misrepresented how the children were recruited

The paper claimed the children were consecutively referred, implying an unbiased clinical sample. In reality, several were recruited through anti-vaccine groups or families involved in the lawsuit funding Wakefield, meaning the sample was deliberately cherry-picked to support his predetermined hypothesis.

4) He altered and falsified data

Comparisons between medical records and the published paper revealed extensive falsification:

• symptoms that began before vaccination were rewritten as occurring after MMR
• gastrointestinal findings were exaggerated or invented
• diagnoses were manipulated to fit his fabricated “autistic enterocolitis” syndrome
• normal clinical results were presented as abnormal.

The tragedy in all this is that a fraudulent study that never should have seen the light of day continues, even now, to erode confidence in life-saving vaccines. This has led to reduced vaccination rates, the resurgence of preventable childhood illnesses, and unnecessary deaths.

It has also inflicted immeasurable harm on autistic people and their families by fuelling stigma and misinformation.

Hassan Vally, Associate Professor, Epidemiology, Deakin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.