Chronic musculoskeletal conditions

What is osteoarthritis?

Osteoarthritis is a chronic condition characterised by the breakdown of the cartilage that overlies the ends of bones in joints. Osteoarthritis mostly affects the hands, spine and joints such as hips, knees and ankles, and usually gets worse over time.

As osteoarthritis progresses, it can become difficult to perform everyday tasks. At first, pain is felt during and after activity, but as the condition worsens, pain may be felt during minor movements or even at rest. Affected joints may also become swollen and tender which can affect fine motor skills.

Osteoarthritis has no specific cause, however several factors contribute to the onset and progression (Chapman & Valdes 2012), including:

• being female
• genetic factors
• excess weight
• joint misalignment
• joint injury or trauma (such as dislocation or fracture)
• repetitive joint-loading tasks (for example, kneeling, squatting and heavy lifting).

How common is osteoarthritis?

Osteoarthritis is the most common form of arthritis in Australia. An estimated 2.2 million (9.3%) Australians have this condition, according to the Australian Bureau of Statistics (ABS) 2017–18 National Health Survey (NHS). Osteoarthritis represented over half (62%) of all arthritic conditions in 2017–18 (ABS 2019).

Although osteoarthritis affects people of all ages, the prevalence increases sharply from the age of 45 years. A total of 1 in 5 Australians (22%) over the age of 45 have osteoarthritis. It is most common in adults aged 75 and over, with just over one-third (36%) of people in this age group experiencing the condition (Figure 1).

Osteoarthritis is also more common among females than males, affecting 10% of females compared with 6.1% of males (after adjusting for age).

Figure 1: Prevalence of self-reported osteoarthritis, by age and sex, 2017–18

Note: refers to people who self-reported that being told that they had osteoarthritis (current and long term) by a doctor or nurse and people who self-reported having osteoarthritis.

Source: AIHW analysis of ABS 2019 (Data table).

Inequalities

For people aged 45 and over, the prevalence of osteoarthritis was slightly lower in Major cities (19%), compared with Inner regional and Outer regional/Remote areas (25% and 23%, respectively).

The prevalence of osteoarthritis was higher for people living in the lowest socioeconomic areas (25%) compared with people in the highest socioeconomic areas (16%). Women had higher rates of osteoarthritis compared with men for all regions and socioeconomic areas (Figure 3).

Figure 2: Osteoarthritis prevalence, by remoteness and socioeconomic area, people aged 45 and over 2017–18

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS 2019 (Data table).

Impact of osteoarthritis

Osteoarthritis can have a profound impact on every aspect of a person's life. Ongoing pain, physical limitations and depression can affect an individual's ability to engage in social, community and occupational activities (Briggs et al. 2016). In Australia, osteoarthritis accounted for 19% of the total burden of disease due to musculoskeletal conditions in 2015 (AIHW 2019a).

Perceived health status

According to the ABS 2017–18 National Health Survey (NHS), people aged 45 and over with osteoarthritis are less likely to perceive their health as excellent or very good compared with people without osteoarthritis. People with osteoarthritis were 2.1 times as likely to describe their health as poor (11%) compared with those without osteoarthritis (5.0%) (Figure 3).

Figure 3: Self-assessed health of people aged 45 and over with and without osteoarthritis, 2017–18

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS 2019 (Data table).

Pain

Osteoarthritis can have a profound impact on a person’s physical health, as joint pain and physical limitations are major symptoms of osteoarthritis. Older people with osteoarthritis can also be more prone to falls compared with those without osteoarthritis. This increased risk is due to a number of factors caused by osteoarthritis, such as decreased physical activity, joint instability, medication use and pain (Cooper et al. 2010).

In 2017–18, over half of people (58%) with osteoarthritis experienced ‘moderate’ to ‘very severe’ pain in the last 4 weeks. People with osteoarthritis were also 2.9 times as likely to have ‘very severe pain’ (4.9%) compared with those without the condition (1.7%) (Figure 4). In addition, almost half (48%) of people with osteoarthritis described their pain as having a ‘moderate’ to ‘extreme’ interference with their normal work during the last 4 weeks, compared with 22% in people without osteoarthritis.

Figure 4: Pain^(a) experienced by people aged 45 and over with and without osteoarthritis, 2017–18

a. Bodily pain experienced in the 4 weeks prior to interview.

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS 2019 (Data table).

Psychological distress

People with osteoarthritis commonly experience anxiety, depression and other mental health issues. Pain, physical limitations, poor treatment outcomes and increased pharmacotherapy can impact a person’s mental health and, consequently, their quality of life (Sharma et al. 2016).

According to the NHS 2017–18, one in 5 (21%) Australian adults with osteoarthritis experienced high or very high levels of distress. This was 2 times as high as those without the condition (11%) (Figure 5).

Figure 5: Psychological distress^(a) experienced by people aged 45 and over with and without osteoarthritis, 2017–18

b. Psychological distress is measured using the Kessler Psychological Distress Scale (K10), which involves 10 questions about negative emotional states experienced in the previous 4 weeks. The scores are grouped into Low: K10 score 10–15, Moderate: 16–21, High: 22–29, Very high: 30–50.

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS 2019 (Data table).

Economic impact

In 2015–16, osteoarthritis cost the Australian health system an estimated $3.5 billion, representing 28% of disease expenditure on musculoskeletal conditions and 3% of total disease expenditure (AIHW 2019b).

Treatment and management of osteoarthritis

At present, there is no cure for osteoarthritis and the disease is long-term and progressive. Treatment for osteoarthritis aims to manage symptoms, increase mobility and maximise quality of life.

Treatment options for osteoarthritis include:

• physical activity
• weight management
• medication
• joint replacement surgery.

Physical activity

Exercise is an important and effective component in both management and prevention of osteoarthritis. Exercise helps improve symptoms (especially pain and joint stiffness) and quality of life by increasing range of motion (the ability to move joints through their full motion), strengthening muscles around affected joints, assists in weight control and reduces risk of other chronic diseases (e.g. diabetes and cardiovascular disease). Exercise is also beneficial for other comorbidities and overall health (RACGP 2018). A GP or Exercise Physiologist should be consulted before undertaking an exercise program.

Weight management

Being overweight increases the risk of developing osteoarthritis, due to the increased load on weight bearing joints and increased stress on cartilage. Weight management is strongly recommended for people with knee and/or hip osteoarthritis who are overweight or obese (RACGP 2018). For people with existing osteoarthritis and who are overweight or obese, weight loss can help reduce symptoms (RACGP 2018). Weight loss should be combined with exercise for the greatest benefits (RACGP 2018).

A GP or Dietitian can be consulted to discuss weight loss/management strategies.

Medications

Treatment of osteoarthritis with medication aims to relieve pain, reduce inflammation and improve functioning and quality of life. Analgesics, or pain medications, are commonly used to manage the pain of osteoarthritis. Analgesics include paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics. For those with hip and/or knee osteoarthritis requiring pain relief, it may be reasonable to trial the use of paracetamol or NSAIDs for a short period and then discontinue use if it is not effective (RACGP 2018). Corticosteroid injections may also be recommended for short term pain relief for hip and/or knee osteoarthritis if appropriate (RACGP 2018). Opioids are not recommended for the treatment of hip and/or knee osteoarthritis (RACGP 2018).

General practitioners and osteoarthritis treatment

General practitioners (GPs) are usually the first point of contact with the health care system for people with osteoarthritis (McKenzie & Torkington 2010; RACGP 2018) and are ideally placed to play the role of care coordinator to ensure treatment continuity (RACGP 2018). GP management of osteoarthritis may include assessment and diagnosis, referral to other health services, prescribing medication and providing education about the condition.

Osteoarthritis is among the most commonly managed conditions in general practice. About 2.6 of every 100 encounters were for osteoarthritis in 2015–16 (Britt et al. 2016). This has not changed significantly since 2006–07 (Figure 6).

There is currently no nationally consistent primary health care data collection monitoring provision of care by GPs. Note that statistics on general practice activities based on Bettering the Evaluation and Care of Health (BEACH) data are derived from a sample survey of GPs and their encounters with patients, and need to be interpreted with some caution.

Figure 6: Rate of osteoarthritis managed by GPs, 2006–07 to 2015–16

Source: Britt et al. 2016 (Data table).

Hospitalisation and the treatment of osteoarthritis

Based on the AIHW National Hospital Morbidity Database (NHMD), in 2020–21:

• There were 285,000 hospitalisations with a principal diagnosis of osteoarthritis, a rate of 1,100 hospitalisations per 100,000 population.
• More than half (56%) of osteoarthritis hospitalisations were for females.
• People aged 70–74 years had more hospitalisations and bed days compared to younger and older age groups, while people aged 75–79 years had the most hospitalisations per population compared to other age groups.
• Average length of overnight stays increased substantially with age, more than doubling between age groups 45–49 and 85+ (Figure 7).

Figure 7: Rate of hospitalisation for osteoarthritis by sex and age, 2020–21

The hospitalisation rate for osteoarthritis increased steadily between 2015–16 and 2018–19, however, the hospitalisation rate  dropped in 2019–20, from 1,300 separations per 100,000 population in 2018–19 to 1,100 separations per 100,000 population in 2019–20 among women, and from 950 separations per 100,000 population to 860 separations per 100,000 among men. This may have been due to widespread public health mandates to pause elective surgery due to the COVID-19 pandemic. In 2020–21 the hospitalisation rate returned to near or slightly above the pre-pandemic rate. In all years, the rate of hospitalisations was higher for females than males (Figure 8). Data prior to 2015–16 are not presented because rehabilitation hospitalisations were coded differently before this year.

The total bed days for hospitalisations with an osteoarthritis principal diagnosis has remained steady at just over 900,000 bed days between 2015–16 and 2020–21 except for a drop in 2019–20 to 819,000. The average length of stay for overnight separations has steadily decreased from 6.2 days in 2015–16 to 5.3 days in 2020–21.

Figure 8. Rate of hospitalisations for osteoarthritis, 2015–16 to 2020–21

Between 2010–11 and 2020–21, the acute care hospitalisation rate for osteoarthritis remained relatively stable (Figure 9). This is with the exception of 2019–20, where there was a dip in hospitalisations in line with the widespread public health mandates to pause elective surgery due to the COVID-19 pandemic. Over the same period, the hospitalisation rate for other care types, including sub-acute and non-acute care for osteoarthritis increased 1.7 times.

The average length of hospitalisations for acute care has steadily decreased between 2010–11 and 2020–21 from 4.6 to 3.9 bed days. The average length of stay for non-acute care decreased from a higher base of 5.1 days in 2010–11 to a lower last value of 3.5 days in 2020–21.

In 2020–21, osteoarthritis was the most common reason for rehabilitation care with arthrosis of knee accounting for 25% and arthrosis of hip accounting for 9.0% of all rehabilitation hospitalisations (AIHW 2022). The primary purpose of rehabilitation care is to improve functioning of a patient with an impairment, activity limitation, or participation restriction due to a health condition.

Figure 9: Rate of hospitalisations for osteoarthritis (any diagnosis), by care type, 2010–11 to 2020–21

Joint replacement surgery

Osteoarthritis is also the most common condition leading to hip and knee replacement surgery in Australia (AOANJRR 2019). Joint replacement is a cost-effective and clinically effective treatment for severe osteoarthritis (RACGP 2018). Clinical guidelines in Australia recommend considering joint replacement surgery for severe osteoarthritis if all conservative treatment options have failed (RACGP 2018). These procedures restore joint function, help relieve pain and improve the quality of life of the affected person.

In 2020–21, 62,800 knee replacements (245 per 100,000 population) and 38,800 hip replacements (150 per 100,000 population) were performed in hospitalisations with a principal diagnosis of osteoarthritis. The rate of knee or hip replacements was lowest in people aged under 45, increased with age to 75–79, and then decreased among those aged 80 and over (Figure 10).

The average length of stay for knee and hip replacements shows a similar trend across age groups, increasing with age from around 4 days for people aged 45–49 to around 6 days for people aged 85 and over.

Figure 10: Rate of total knee and hip replacements for osteoarthritis, by age, 2020–21

Between 2010–11 and 2020–21, the age-standardised rate of joint replacement surgery in hospitalisations where osteoarthritis was the principal diagnosis generally increased, by:

• 22% for total knee replacement (from 160 to 195 per 100,000 population)
• 29% for total hip replacement (from 95 to 120 per 100,000 population) (Figure 11).

Figure 11: Trends in total knee and hip replacements for osteoarthritis, 2010–11 to 2020–21

Comorbidities of osteoarthritis

People with osteoarthritis often have other chronic conditions. Comorbidity is the term used when two or more health conditions occur at the same time. For this analysis, the selected comorbidities were reported:

• heart, stroke and vascular disease
• kidney disease
• arthritis
• mental and behavioural conditions
• asthma
• diabetes
• chronic obstructive pulmonary disease (COPD)
• osteoporosis
• cancer.

According to the ABS NHS 2017–18, among people aged 45 and over with osteoarthritis:

• 38% also had back problems compared with 23% of people without osteoarthritis.
• 31% also had mental and behavioural conditions compared with 20% of people without osteoarthritis.
• 22% also had osteoporosis compared with 6% of people without osteoarthritis (Table 2.5).

Most chronic conditions are more common in older age groups. The average age of people with osteoarthritis is older than the average age of the general population, so people with osteoarthritis are more likely to have age-related comorbidities.

After adjusting for differences in the age structure of people with and without osteoarthritis, the rates of the selected comorbidities (excluding cancer) remained significantly higher for people with osteoarthritis compared with those without (Figure 12). There was no significant difference for cancer. It is important to note that regardless of the differences in age structures, having multiple chronic health problems is often associated with worse health outcomes (Parekh et al. 2011), in addition to a poorer quality of life (McDaid et al. 2013) and more complex clinical management and increased health costs.

Figure 12: Prevalence of other chronic conditions in people aged 45 and over with and without osteoarthritis, 2017–18

Notes:

1. Age-standardised to the 2001 Australian population.
2. Proportions do not total 100% as one person may have more than one additional diagnosis.

Source: AIHW analysis of ABS 2019 (Data table).