A recent study reported a significant increase in rates of knee osteoarthritis found in individuals living today compared to previous generations (http://www.pnas.org/content/114/35/9332). Researchers at Harvard University studied skeletal remains of people over the age of 50 in the early industrial era (1800’s to early 1900’s) and compared them to those of people living during the late 1900’s to the year 2000.  They found evidence of knee osteoarthritis in 6% of people who lived in the early industrial period, and 16% of people living in the post-industrial period. An important aspect of the study was that the researchers controlled for age and BMI, factors that are associated with the presence of osteoarthritis. In other words, there is approximately a 2-fold increase in knee osteoarthritis rates today compared to previous generations, and this increase is not related to increased rates of obesity. 

It is commonly accepted that people who are over-weight or obese are more likely to develop hip or knee osteoarthritis.  Although higher BMI is considered a risk factor for osteoarthritis, this study suggests that there are other risk factors at play. The authors of the study speculate that one factor that deserves more study is the role of physical inactivity in the development of osteoarthritis. Physical activity places demands on the musculoskeletal system that help to strengthen body tissues. This in turn offers protection to the joints. It is conceivable that inactivity leads to a loss of joint integrity. 

One thing we do know is that osteoarthritis represents a mechanical breakdown of joints. There is an imbalance between joint loading (for example during sports participation or functional activities) and joint integrity. 

Physical therapists can help people restore the balance between joint loading and joint integrity. Prescription of specific exercises is a key ingredient to improving joint function. There is overwhelming evidence that exercises are effective in treating osteoarthritis. Regular exercise is also the best prevention for osteoarthritis.

Marcia Miller Spoto PT, DC, OCS