Women's Health Matters

Text Size
Jump to body content

Taking a fresh look at osteoarthritis: new ideas about OA and its treatment

Author:  Patricia Nicholson

Osteoarthritis (OA) is one of the most common conditions affecting older Canadians. It is also the most common form of arthritis, accounting for about three-quarters of the approximately four million arthritis cases in Canada.

OA is a complex condition that can be both painful and frustrating. Dr. Gillian Hawker, senior scientist at the Women’s College Research Institute and physician-in-chief of the department of medicine at Women’s College Hospital, says that doctors and researchers are taking a fresh look at OA – what causes OA, and how best to prevent and manage OA and its symptoms.

The good news is that although OA is more common as one gets older, OA should not be considered a natural and inevitable consequence of age.

‘It is age-related, but not everyone gets it,’ Dr. Hawker said during a presentation at Women’s College Hospital in October 2010. ‘It is not a normal part of aging.’

Osteoarthritis usually affects the hands, feet, knees, hips and lower back. When it affects multiple joints, it is called generalized osteoarthritis.

OA defined

An important part of preventing and treating a condition is understanding what it is. In 2009, the Osteoarthritis Research Society International (OARSI) offered a new definition of osteoarthritis:

a progressive disease of synovial joints that represents failed repair of joint damage resulting from stresses that may be initiated by an abnormality in any of the joint tissues, which leads to breakdown of cartilage and the underlying bone.

‘That’s a bit of a mouthful,’ Dr. Hawker said. She explained some of the important points in the new definition:

  • It’s not simply the result of the wear and tear of aging on the joint cartilage, but rather the result of a failed attempt by the body to repair joint tissues that are damaged by abnormal stresses, such as ligament or meniscus injury.
  • The thinning and destruction of cartilage that characterizes OA is a result of this failed repair.
  • It’s a progressive disease, not a degenerative one. OA does get gradually worse over time (disease progression), but OA is NOT the result of cartilage degeneration. Instead, cartilage degeneration is actually an end result of OA: it begins with abnormalities that may be genetic, or may be caused by injury, illness, muscle or nerve problems, or many other origins.

Osteoarthritis is a complex condition, with complex causes, symptoms and risk factors. This makes OA challenging to prevent, and treat. Studies indicate that less than half of OA patients are getting the comprehensive care – including drug and non-drug therapies, including lifestyle interventions - they need.

There are several barriers to successful OA treatment, including:

  • the belief that OA is a natural and inevitable part of aging that can’t be treated
  • because OA affects older adults, patients often have other conditions and take other medications that can interfere with treatment
  • costs of uninsured services such as physical therapy
  • misconceptions about joint replacement surgery

The structural changes and thinning cartilage in the joints that characterize OA do not always directly coincide with OA symptoms. One of the puzzling features of osteoarthritis is that in some people, the structural signs of OA can be seen in X-rays, but causes no pain. Other people experience substantial pain, but their OA can’t be seen on X-rays, or appears minimal. More sensitive imaging techniques, such as MRI, have helped, but the structural changes in the joints and symptoms such as pain still do not overlap perfectly in OA.

Dr. Hawker focused on the importance of addressing symptoms, since it is symptoms – particularly pain and fatigue – that patients want to manage.

‘People don’t seek care because their X-ray is abnormal. They seek care because they’re in pain,’ she said.

Why pain matters

Dr. Hawker and her colleagues have been following for more than a decade a group of over 2000 people living with painful OA in Ontario. To find out more about their symptoms, researchers have conducted focus groups and detailed interviews.

Their results have found that that intensity of the pain is very important, as is the way pain affects their sleep and mood. One surprising finding was that the predictability of pain was very important to people with OA.

‘If the pain was predictable they could plan around it, pace themselves, organize around things they knew were going to make their pain worse, such as going grocery shopping,’ Dr. Hawker explained. ‘But if they experienced unpredictable pain, they really couldn’t plan around it.’

People who had unpredictable pain were more likely to give up activities and limit their social lives, which lowered their quality of life.

Pain affected mood in several important ways: it caused frustration when a patient was unable to do activities because of their OA pain, and it also caused fear and worry about the future, and whether it would be possible to continue living independently.

The link between pain and sleep can be described as a vicious circle. Pain makes it difficult to fall asleep, causes anxiety at bedtime, and alters the phases of sleep, Dr. Hawker explained. Those changes result in sleep deprivation and disrupted sleep, which in turn reduce a person’s pain threshold, which actually makes the pain worse.

Sleep, and the fatigue caused by chronic pain, may also be linked to another mood issue: the depression that is common – but undertreated – in people with OA. Dr. Hawker estimates that about one in five OA patients is affected by depression.

‘We know that it is inadequately assessed and treated in these people and there are very effective management approaches in older individuals,’ she said. ‘We do believe that effective treatment of OA pain may decrease depression – and vice versa.’

Because pain is what leads to disability, sleep disruption, fatigue and eventually depressed mood, it is pain that needs to be the target for treatment, Dr. Hawker said.

What kind of pain?

There is mounting evidence that the traditional approach to OA pain may be targeting the wrong kind of pain in some patients. Dr. Hawker explained that the treatment guidelines for OA focus on painkillers such as acetaminophen, anti-inflammatory drugs and cortisone injections. However, these drugs all target a type of pain called nociceptive pain – the kind of pain that is caused by tissue injury. Nociceptive pain is the result of receptors called nociceptors relaying pain signals to the brain.

It’s now believed that some OA patients are experiencing a different kind of pain: neuropathic pain, which originates in the nervous system. Neuropathic and nociceptive pain feel different, behave differently, have different causes and are treated differently.

In OA, neuropathic pain may be due to a process called central pain sensitization, Dr. Hawker explained. When people live with chronic nociceptive pain, it can change the way the central and peripheral nervous systems process the pain, and can actually lead to an amplification of the pain. Through that amplification, the pain becomes predominantly neuropathic rather than nociceptive.

In focus groups and on questionnaires, Dr Jackie Hochman, a rheumatologist and member of the OA research team at Women’s College, found that people with OA often described their pain using terms that are associated with neuropathic pain, such as burning, tingling, deep pain.

Neuropathic pain is often treated with medications such as antidepressants and anti-seizure drugs, rather than traditional ‘pain killers.’

‘We need to consider not only the pain, but the downstream impact of the pain and the type of pain, and match the symptoms as much as we can,’ Dr. Hawker said.

Managing OA

There is no cure for osteoarthritis, but there are effective approaches to managing its symptoms and preventing its progression.

OA is the most likely form of arthritis to cause disability: for every person disabled by rheumatoid arthritis, there are seven disabled by osteoarthritis. Women are twice as likely as men the same age to be disabled by OA.

Some of the most important risk factors for disease progression include conditions that overload the joints, such as obesity, poorly aligned joints (such as bowed or knock-kneed legs), weak muscles around the joints, joint deformities, injuries and nerve damage.

Because obesity places strain on the joints, weight management is an important part of managing OA, as is maintaining and improving the physical functioning of the joints. One study found that in women who were overweight, every five kilograms of weight they lost reduced their risk of knee osteoarthritis by 50 per cent.

Most studies have found that people with moderate OA are better off doing exercise than being inactive, Dr. Hawker noted. In fact, studies have found that exercises such as tai chi are as effective in treating OA as glucosamine, acetaminophen and acupuncture.

Occupational therapy and physical therapy can improve joint alignment and reduce strain on the joint. Assistive devices such as shoe insoles, braces, canes and other devices can also reduce joint stress.

Some researchers are now focusing on neuromuscular training, which encompasses not just muscle strength and use, but also how the muscles actually support the joint when it’s in action. The goal is to teach the muscles to move the joints in a safe, aligned way, so that pressure and stress are exerted at the correct points in the joint.

Pain treatments traditionally used in OA include acetaminophen, NSAIDs, glucosamine sulphate, acupuncture, joint injections such as cortisone and hydraluronic acid, and orthopedic surgery. Current research suggests that some OA patients may need different types of pain relief to treat neuropathic pain. Treating conditions that often occur with OA, such as depression and sleep disorders, may also help to manage pain.

Future approaches to managing OA may need to involve both the condition itself as well as its effects, Dr. Hawker said. In OA, these can be very different issues.

‘We need to consider the disease and the illness – joint damage versus symptoms – as distinct entities,’ she said. Both need to be addressed, which will likely require a dual approach. ‘Because it’s unlikely we’re going to have a treatment for the structural changes that is also going to be effective for the symptoms.’

Jump to top page

A Question of Health

This month's topic:Pregnancy after 35: What you should know about advanced maternal age

Women are increasingly delaying pregnancy until later in life, especially in larger Canadian cities.

  • A publication of:
  • Women's College Hospital