Knee osteoarthritis – a recent phenomenon?
Many specialists feel that knee osteoarthritis (OA) has markedly increased in the 20th century. Commonly believed to be the result of a greater life expectancy and higher BMI in Western societies. However there appears to be no strong evidence to support this commonly held view. So it was with this in mind that a team from Harvard led by Ian J. Wallace tried to investigate this further.
A historical perspective
The team did this by extensive analysis of long term trends in skeletons from the early industrial era (1800s to 1900s) through to the modern postindustrial era (1900s to 2000s). Well over 2000 skeletons in total who’s BMI and age (all being 50 years and over) were recorded at death . A further 176 individuals from prehistoric hunter gatherers to early farmers were also assessed.
Osteoarthritis has doubled in prevalence
The findings were fascinating. Knee OA was found to be at 16% within the postindustrial individuals compared to only 6% and 8% in the early industrial and prehistoric skeletons respectively. Furthermore after controlling for BMI, age and other variables knee OA was still 2.1 times as common. So why in modern era are we seeing an increase in OA if BMI and old age are not the cause?
Change in lifestyles
In conclusion the authors suggest that this is highly likely to be the result of a reduction in activity levels in the postindustrial period, due to a monumental shift in work lifestyles. The days in which many of us would have been working the land or doing demanding physical loading in the early industrial era have long gone. Culturally there has been a shift towards service sector jobs which ultimately can lead to more sedentary lives. Further research in this area will be necessary but it is a strong argument that activity and exercise actually keep our joints strong and healthy. Rather than wear them out through wear and tear!