What is osteoarthritis?

Osteoarthritis is a chronic condition characterised by the breakdown of the cartilage that overlies the ends of bones in joints. This results in the bones rubbing together, causing pain, swelling and loss of motion (Figure 1). Osteoarthritis mostly affects the hands, spine and joints such as hips, knees and ankles, and usually gets worse over time.

Figure 1: Comparison of healthy joint and joint with osteoarthritis

This image compares the anatomy of a healthy joint with a joint affected by osteoarthritis. The image shows bone spurs, thinned cartilage and bone ends that rub together in osteoarthritis compared with a normal joint

Source: AIHW 2015. Musculoskeletal fact sheet: Osteoarthritis. Arthritis series no. 22. Cat. no. PHE 186. Canberra: AIHW. 

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 [1, 2, 3], 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 [4].

1 in 11

Australians (9%) have osteoarthritis

Although osteoarthritis affects people of all ages, the prevalence increases sharply from the age of 45 years. 1 in 5 Australians (21%) 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 2).

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

Figure 2: Prevalence of self-reported osteoarthritis, by age and sex, 2017–18

This vertical bar chart compares the percentage of self-reported osteoarthritis across various age groups, by sex. Osteoarthritis is highest in the 75+years age groups for both males (26%25) and females (44%25). Osteoarthritis was lowest among the 0–44 years age group for both males and females (1%25).

Note: refers to people who self-reported that they were diagnosed by a doctor or nurse as having osteoarthritis (current and long term) and also people who self-reported having osteoarthritis.

Source: AIHW analysis of ABS 2019 [4] (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 (26%) 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 3: Osteoarthritis prevalence, by remoteness and socioeconomic area, people aged 45 and over 2017–18

This horizontal bar chart compares osteoarthritis prevalence in males and females aged 45 and over, by remoteness (Major cities, Inner regional and Outer regional/Remote) and socioeconomic area. Major cities had the lowest prevalence for both males (14%25) and females (24%25) compared to inner regional (19%25 and 30%25 for males and females, respectively) and outer regional/remote (18%25 and 28%25, respectively). For socioeconomic area, prevalence was higher in ‘group 1’ (lowest socioeconomic area) for both males (19%25) and females (31%25). Osteoarthritis prevalence was lowest in ‘group 5’ (highest socioeconomic area) for both males (13%25) and females (20%25).

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS 2019 [4] (Data table).

References

  1. Chapman K & Valdes AM 2012. Genetic factors in OA pathogenesis. Bone 51:64–72.
  2. Lementowski PW & Zelicof SB 2008. Obesity and osteoarthritis 2008. The American Journal of Orthopaedics 37(3):148–151.
  3. Foley S, Ding C, Cicuttini F & Jones G 2007. Physical activity and knee structural change: a longitudinal study using MRI. Medicine and Science in Sports and Exercise 39:426–434.
  4. ABS 2019. Microdata: National Health Survey, 2017–18, detailed microdata, DataLab. ABS cat. no. 4324.0.55.001. Canberra: ABS. Findings based on AIHW analysis of ABS microdata.