Hip and knee replacements are some of the most frequently performed and effective surgeries worldwide. The main indication for hip and knee replacement (joint replacement surgery) is osteoarthritis, which leads to reduced function and quality of life.
Osteoarthritis is a degenerative form of arthritis characterised by the wearing down of cartilage that cushions and smooths the movement of joints – most commonly for the hip and knee. It causes pain, swelling and stiffness resulting in a loss of mobility and function. Osteoarthritis is one of the ten most disabling diseases in developed countries. Worldwide, estimates show that 10% of men and 18% of women aged over 60 years have symptomatic osteoarthritis, including moderate and severe forms (WHO, 2014[1]).
Age is the strongest predictor of the development and progression of osteoarthritis. It is more common in women, increasing after the age of 50 especially in the hand and knee. Other risk factors include obesity, physical inactivity, smoking, excessive alcohol consumption and injuries. While joint replacement surgery is mainly carried out among people aged 60 and over, it can also be performed on people at younger ages.
In 2017, Germany, Austria, Switzerland, Finland, Luxembourg and Belgium were among the countries with the highest rates for hip and knee replacement (Figure 9.12 and Figure 9.13). The OECD averages are 182 per 100 000 population for hip replacement, and 135 per 100 000 for knee replacement. Mexico, Portugal, Israel, Ireland and Korea have low hip and knee replacement rates. Differences in population structure may explain part of this variation across countries, and age standardisation reduces it to some extent. Nevertheless, large differences persist and the country ranking does not change significantly after age standardisation (McPherson, Gon and Scott, 2013[2]).
National averages can mask important variation in hip and knee replacement rates within countries. In Australia, Canada, Germany, France and Italy, the rate of knee replacement is more than twice as high in some regions than others, even after age-standardisation (OECD, 2014[3]). Alongside the number of operations, the quality of hip and knee surgery (see indicator on “Hip and knee surgery” in Chapter 6) and waiting times (see indicator on “Waiting times for elective surgery” in Chapter 5) are also critical for patients.
Since 2000, the number of hip and knee replacements has increased rapidly in most OECD countries (Figure 9.14 and Figure 9.15). On average, hip replacement rates increased by 30% between 2007 and 2017 and knee replacement rates by 40%. This aligns with the rising incidence and prevalence of osteoarthritis, caused by ageing populations and growing obesity rates in OECD countries. For example, in the United States, the prevalence of knee osteoarthritis has more than doubled since the mid-20th century (Wallace et al., 2017[4]).
Most OECD countries show increasing trends of varying degrees, but Ireland and Luxembourg show slower growth than the average, these are also the only OECD countries to show a decrease in hip replacements rates from 2007.
