Having an x-ray to diagnose knee arthritis might make you more likely to consider potentially unnecessary surgery

Osteoarthritis is a leading cause of chronic pain and disability, affecting more than two million Australians.

Routine x-rays aren’t recommended to diagnose the condition. Instead, GPs can make a diagnosis based on symptoms and medical history.

Yet nearly half of new patients with knee osteoarthritis who visit a GP in Australia are referred for imaging. Osteoarthritis imaging costs the health system A$104.7 million each year.

Our new study shows using x-rays to diagnose knee osteoarthritis can affect how a person thinks about their knee pain – and can prompt them to consider potentially unnecessary knee replacement surgery.

What happens when you get osteoarthritis?

Osteoarthritis arises from joint changes and the joint working extra hard to repair itself. It affects the entire joint, including the bones, cartilage, ligaments and muscles.

It is most common in older adults, people with a high body weight and those with a history of knee injury.

Many people with knee osteoarthritis experience persistent pain and have difficulties with everyday activities such as walking and climbing stairs.

How is it treated?

In 2021–22, more than 53,000 Australians had knee replacement surgery for osteoarthritis.

Hospital services for osteoarthritis, primarily driven by joint replacement surgery, cost $3.7 billion in 2020–21.

While joint replacement surgery is often viewed as inevitable for osteoarthritis, it should only be considered for those with severe symptoms who have already tried appropriate non-surgical treatments. Surgery carries the risk of serious adverse events, such as blood clot or infection, and not everyone makes a full recovery.

Most people with knee osteoarthritis can manage it effectively with:

• education and self-management
• exercise and physical activity
• weight management (if necessary)
• medicines for pain relief (such as paracetamol and non-steroidal anti-inflammatory drugs).

Debunking a common misconception

A common misconception is that osteoarthritis is caused by “wear and tear”.

However, research shows the extent of structural changes seen in a joint on an x-ray does not reflect the level of pain or disability a person experiences, nor does it predict how symptoms will change.

Some people with minimal joint changes have very bad symptoms, while others with more joint changes have only mild symptoms. This is why routine x-rays aren’t recommended for diagnosing knee osteoarthritis or guiding treatment decisions.

Instead, guidelines recommend a “clinical diagnosis” based on a person’s age (being 45 years or over) and symptoms: experiencing joint pain with activity and, in the morning, having no joint-stiffness or stiffness that lasts less than 30 minutes.

Despite this, many health professionals in Australia continue to use x-rays to diagnose knee osteoarthritis. And many people with osteoarthritis still expect or want them.

What did our study investigate?

Our study aimed to find out if using x-rays to diagnose knee osteoarthritis affects a person’s beliefs about osteoarthritis management, compared to a getting a clinical diagnosis without x-rays.

We recruited 617 people from across Australia and randomly assigned them to watch one of three videos. Each video showed a hypothetical consultation with a general practitioner about knee pain.

One group received a clinical diagnosis of knee osteoarthritis based on age and symptoms, without being sent for an x-ray.

The other two groups had x-rays to determine their diagnosis (the doctor showed one group their x-ray images and not the other).

After watching their assigned video, participants completed a survey about their beliefs about osteoarthritis management.

What did we find?

People who received an x-ray-based diagnosis and were shown their x-ray images had a 36% higher perceived need for knee replacement surgery than those who received a clinical diagnosis (without x-ray).

They also believed exercise and physical activity could be more harmful to their joint, were more worried about their condition worsening, and were more fearful of movement.

Interestingly, people were slightly more satisfied with an x-ray-based diagnosis than a clinical diagnosis.

This may reflect the common misconception that osteoarthritis is caused by “wear and tear” and an assumption that the “damage” inside the joint needs to be seen to guide treatment.

What does this mean for people with osteoarthritis?

Our findings show why it’s important to avoid unnecessary x-rays when diagnosing knee osteoarthritis.

While changing clinical practice can be challenging, reducing unnecessary x-rays could help ease patient anxiety, prevent unnecessary concern about joint damage, and reduce demand for costly and potentially unnecessary joint replacement surgery.

It could also help reduce exposure to medical radiation and lower health-care costs.

Previous research in osteoarthritis, as well as back and shoulder pain, similarly shows that when health professionals focus on joint “wear and tear” it can make patients more anxious about their condition and concerned about damaging their joints.

If you have knee osteoarthritis, know that routine x-rays aren’t needed for diagnosis or to determine the best treatment for you. Getting an x-ray can make you more concerned and more open to surgery. But there are a range of non-surgical options that could reduce pain, improve mobility and are less invasive.