Between 1998 and 2008, European countries saw a huge increase in hip and knee replacements. This trend is expected to continue, as the prevalence of osteoarthritis goes up during the next few years. Two main factors, which come as no surprise, can be blamed for the rise in this condition--an aging population and the rise of obesity. The report, Health at a Glance: Europe 2010, also states that there is a pretty big difference between the rate of hip and knee replacements across various countries in Europe. It attributes these wide differences to the prevalence of osteoarthritis, the ability to deliver and pay for the procedures, and clinical treatment guidelines and practices. View hip and knee replacements by country.

Hip replacement surgery trend from 1998 to 2008. Source: OECD Health Data 2010; Euro Statistics Database.	Knee replacement surgery trend from 1998 to 2008. Source: OECD Health Data 2010; Euro Statistics Database.