What is osteoarthritis?

Osteoarthritis (OA) 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. OA 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.

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

As OA 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.

OA 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?

OA is the most common form of arthritis in Australia. About 2.1 million (9%) Australians report having this condition, according to the Australian Bureau of Statistics (ABS) 2014–15 National Health Survey (NHS). OA represented over half (59%) of all arthritic conditions in 2014–15 [5].

1 in 5 Australians aged over 45 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 80 years and older, with just over one-third (35%) of people in this age group reporting the condition (Figure 2).

Osteoarthritis is also more common in females than males, affecting 10% of females compared to 6% of males (after adjusting for age).

Figure 2: Prevalence of osteoarthritis, by age and sex, 2014–15

This vertical bar chart compares the percentage of self-reported osteoarthritis across various age groups, by sex. Osteoarthritis is highest in the 80+years age groups for both males (24%25) and females (44%25). Osteoarthritis was lowest among the 0–15 years age group for both males and females (0.0%25).

Source: AIHW analysis of ABS Microdata: National Health Survey (NHS) 2014–15. ABS cat. no. 4324.0.55.001. Canberra: ABS. (Data table).

Trends

Since 2001, there has been a slight increase in the age-standardised prevalence of OA, from 7.5% to 8.1% in 2014–15. Prevalence increased slightly higher among females compared to males.

Figure 3: Prevalence rate of osteoarthritis, by sex, 2001 to 2014–15

This line graph compares the prevalence of osteoarthritis between 2001 to 2014–15, by sex. Osteoarthritis increased from 5.7%25 for males and 9.2%25 for females in 2001, to 5.9%25 for males and 10%25 females in 2014–15.

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS 2001, 2004–05, 2007–08, 2011–12 and 2014–15 National Health Surveys. Canberra: ABS. (Data table).

Inequalities

The prevalence of OA is not significantly different in Major cities, Inner regional, and Outer regional and Remote areas. The proportion of Australians who reported having OA in Major cities was 7.7%, and was lower compared with Inner regional (9.1%) and Outer regional and Remote areas combined (9.3%).  

The prevalence of OA was higher for areas of lowest socioeconomic status (9.5%) compared to areas of highest socioeconomic status (7.2%) (Figure 4).

Figure 4: Osteoarthritis prevalence, by remoteness area and socioeconomic group, 2014–15

This horizontal bar chart compares osteoarthritis prevalence in males and females, by remoteness (Major cities, Inner regional and Outer regional/Remote) and socio-economic group (from most to least disadvantaged). Prevalence was higher in Outer regional/Remote areas for males (7.9%25) and Inner regional for females (11%25). Major cities had the lowest percentage for both males (5.3%25) and females (9.8%25). For socio-economic groups, prevalence was higher in ‘group 1’ (most disadvantaged group) for both males (6.7%25) and females (12%25). Osteoarthritis prevalence was lowest in ‘group 5’ (least disadvantaged group) for males (4.7%25) and ‘group 4’ for females (9.2%25).

Note: Age-standardised to the 2001 Australian population.

Source: AIHW analysis of ABS Microdata: National Health Survey (NHS) 2014–15. ABS cat. no. 4324.0.55.001. Canberra: ABS. (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. AOA (Australian Orthopaedic Association) 2017. Australian Orthopaedic Association National Joint Replacement Registry Lay Summary: Hip and Knee replacement. Annual Report 2017 (supplementary report). Adelaide: AOA.
  5. ABS 2015. National Health Survey: First Results, 2014–15. Canberra: ABS.