While osteoarthritis may be something most people associate with getting older, new research has suggested that ageing may not actually be the main cause of this painful type of arthritis. What is, however, is still a bit of a mystery.
As many as 2.2 million Australians and one in five American adults are living with the condition, but a recent report published in Harvard Magazine has suggested that osteoarthritis develops as a result of activity, or lack thereof, and not old age.
Researchers Ian Wallace and Daniel Lieberman travelled across the US to examine human skeletons collected over many years to figure out if osteoarthritis had always been as common in older people, or if it’s a more recent phenomenon. The condition, which causes pain and stiffness in the knees, neck, back, hips and joints, usually occurs when cartilage around the joints begins to wear away, causing bones to rub together.
Using a process known as paleo-epidemiology, the researchers were able to accurately determines which skeletons showed signs of osteoarthritis (the bones give off a unique polished look in the later stages of the condition). They were then able to compare their data on the incidence of osteoarthritis in older skeletons with modern findings. What they discovered was that cases of osteoarthritis had more than doubled since the second World War.
They concluded that the only way such change could occur so quickly was due to environmental factors. While being overweight could also increase a person’s chance of developing osteoarthritis, it alone doesn’t explain the increased incidence of the condition in recent years.
What they found is that osteoarthritis levels only spiked dramatically after World War II, suggesting that a rise in less-physical jobs could be a contributing factor. Before that time, more people worked more on their feet and rates of osteoarthritis didn’t increase for centuries.
Furthermore, people in modern times are more likely to develop the condition in both knees, while historical cases of osteoarthritis were usually limited to one.
The researchers are currently trying to figure out the specific reason behind the spike and why people living with osteoarthritis are experiencing it differently from those who had it in the past. They acknowledge that physical activity and exercise is known to increase cartilage in the joints, which does go against a lot of current research that suggests wear and tear on the cartilage over a lifetime is to blame for causing the condition.
“We’re looking at osteoarthrosis as a mismatched disease,” Wallace explained to Harvard Magazine. “And trying to figure out how an evolutionary perspective leads to different hypotheses than would a purely clinical perspective.”