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.

A recent study has suggested Shingrix, a relatively new vaccine given to protect older adults against shingles, may delay the onset of dementia.

This might seem like a bizarre link, but actually, research has previously shown an older version of the shingles vaccine, Zostavax, reduced the risk of dementia.

In this new study, published last week in the journal Nature Medicine, researchers from the United Kingdom found Shingrix delayed dementia onset by 17% compared with Zostavax.

So how did the researchers work this out, and how could a shingles vaccine affect dementia risk?

From Zostavax to Shingrix

Shingles is a viral infection caused by the varicella-zoster virus. It causes painful rashes, and affects older people in particular.

Previously, Zostavax was used to vaccinate against shingles. It was administered as a single shot and provided good protection for about five years.

Shingrix has been developed based on a newer vaccine technology, and is thought to offer stronger and longer-lasting protection. Given in two doses, it’s now the preferred option for shingles vaccination in Australia and elsewhere.

In November 2023, Shingrix replaced Zostavax on the National Immunisation Program, making it available for free to those at highest risk of complications from shingles. This includes all adults aged 65 and over, First Nations people aged 50 and older, and younger adults with certain medical conditions that affect their immune systems.

What the study found

Shingrix was approved by the US Food and Drugs Administration in October 2017. The researchers in the new study used the transition from Zostavax to Shingrix in the United States as an opportunity for research.

They selected 103,837 people who received Zostavax (between October 2014 and September 2017) and compared them with 103,837 people who received Shingrix (between November 2017 and October 2020).

By analysing data from electronic health records, they found people who received Shingrix had a 17% increase in “diagnosis-free time” during the follow-up period (up to six years after vaccination) compared with those who received Zostavax. This was equivalent to an average of 164 extra days without a dementia diagnosis.

The researchers also compared the shingles vaccines to other vaccines: influenza, and a combined vaccine for tetanus, diphtheria and pertussis. Shingrix and Zostavax performed around 14–27% better in lowering the risk of a dementia diagnosis, with Shingrix associated with a greater improvement.

The benefits of Shingrix in terms of dementia risk were significant for both sexes, but more pronounced for women. This is not entirely surprising, because we know women have a higher risk of developing dementia due to interplay of biological factors. These include being more sensitive to certain genetic mutations associated with dementia and hormonal differences.

Why the link?

The idea that vaccination against viral infection can lower the risk of dementia has been around for more than two decades. Associations have been observed between vaccines, such as those for diphtheria, tetanus, polio and influenza, and subsequent dementia risk.

Research has shown Zostavax vaccination can reduce the risk of developing dementia by 20% compared with people who are unvaccinated.

But it may not be that the vaccines themselves protect against dementia. Rather, it may be the resulting lack of viral infection creating this effect. Research indicates bacterial infections in the gut, as well as viral infections, are associated with a higher risk of dementia.

Notably, untreated infections with herpes simplex (herpes) virus – closely related to the varicella-zoster virus that causes shingles – can significantly increase the risk of developing dementia. Research has also shown shingles increases the risk of a later dementia diagnosis.

The mechanism is not entirely clear. But there are two potential pathways which may help us understand why infections could increase the risk of dementia.

First, certain molecules are produced when a baby is developing in the womb to help with the body’s development. These molecules have the potential to cause inflammation and accelerate ageing, so the production of these molecules is silenced around birth. However, viral infections such as shingles can reactivate the production of these molecules in adult life which could hypothetically lead to dementia.

Second, in Alzheimer’s disease, a specific protein called Amyloid-β go rogue and kill brain cells. Certain proteins produced by viruses such as COVID and bad gut bacteria have the potential to support Amyloid-β in its toxic form. In laboratory conditions, these proteins have been shown to accelerate the onset of dementia.

What does this all mean?

With an ageing population, the burden of dementia is only likely to become greater in the years to come. There’s a lot more we have to learn about the causes of the disease and what we can potentially do to prevent and treat it.

This new study has some limitations. For example, time without a diagnosis doesn’t necessarily mean time without disease. Some people may have underlying disease with delayed diagnosis.

This research indicates Shingrix could have a silent benefit, but it’s too early to suggest we can use antiviral vaccines to prevent dementia.

Overall, we need more research exploring in greater detail how infections are linked with dementia. This will help us understand the root causes of dementia and design potential therapies.

Ibrahim Javed, Enterprise and NHMRC Emerging Leadership Fellow, UniSA Clinical & Health Sciences, University of South Australia

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