What Actually Causes Osteoarthritis [Part 1: Age]

Have you ever been told that arthritis is completely inevitable once you begin to age?

Most likely you were told this because one of the common risk factors cited for arthritic conditions such as Osteoarthritis (OA) is that of age. The popular notion is that with age, the joints of the body degrade simply as a result of use or ‘wear & tear’. If you have Googled Osteoarthritis, chances are you have seen this explanation come up in a definition more than once!

However, as modern research has shown, this is an oversimplified, incomplete picture. In fact, a number of research papers are now highlighting the error of this dominant messaging, with this review actually mentioning ‘wear and tear’ as a narrative that leads to harmful beliefs. These beliefs often translate to avoidance of movement and exercise to lessen the ‘wearing’.

However, the review goes on to state that exercise appears to be safe with older patients that have knee pain attributable to OA. Granted, there is a lack of compelling conclusions around exercise, but this appears to simply come down to the lack of long term evidence across sufficient exercise types, particularly those which would be considered ‘non-therapeutic’ (e.g. recreational activity).

When we look at other research reviews such as this review of people from all ages with knee OA signs/ symptoms we see a similar overall conclusion: exercise is not harmful. What’s really exciting is that this evidence is in line with emerging and growing data suggesting that even vigorous exercise such as running, not leading to any worsening of OA symptoms or structural progression.

Furthermore, a 2015 review has gone as far as listing 21 consensus statements on what people need to know about OA, with the 4th statement being: “OA is not an inevitable part of getting older”. This review details some of the crucial pieces of misinformation that are commonly spread about OA, as well as the best advice regarding what should be done to manage it.

So if wear and tear isn’t the complete picture, what actually contributes to OA when we age?

Firstly we need to explain the concept of our body being an adaptive organism. It constantly responds to various stimuli in order to cause adaptation (e.g. muscle growth) or maladaptation (i.e. osteoarthritic degeneration). There are a multitude of factors that lead to these adaptations taking place, all of which are triggered by the demands we face every single day.⁠ In brief, the maladaptations that occur as a result of certain stimuli we face (e.g. Injury, inflammation and all the other factors we will talk about in this series) are what leads to osteoarthritis coming about in the first place. What then happens with ageing, is that the factors that lead to OA developing become more exacerbated, due to our body lacking the ability to recover as effectively.

It can’t be refuted that there is a definite correlation between age and an increase in the likelihood of developing OA. In fact, recent evidence has shown that between 30-40% of people over the age of 65 will have some form of OA. However, as we said before, this increase in OA prevalence is mostly a result of the factors associated with ageing. These are the same factors that are associated with decreased physical activity as a result of ageing. They include: a decrease in muscle function, an increase in body fat % and an associated increase in inflammatory mediators that contribute to the development of OA (all of which are touched upon in the other articles within this series).

We also know that with ageing, our body begins to take longer to undergo repair and recovery (Such as the turnover of bone and key cells in the cartilage, known as proteoglycans) – See more on the comprehensive pathophysiology. We don’t exactly know why things slow as we age, however one popular theory is that with age we become more exposed to oxidative stress and factors that express our immune response. The article linked suggests a whole host of other factors that contribute to increased inflammation (e.g. increased adipose tissue leading to systemic inflammation), which are also associated with age. The bottom line is that with age, we aren’t able to recover as well so we have to be extra careful to ensure we are addressing the factors that matter when it comes to our condition.

What we can take from this is that if we can mitigate the negative factors that are associated with ageing that happen to cause maladaptation, we can help to stave of OA for the long term. These negative factors stem from poor lifestyle choices. We break down these lifestyle choices into three main things (more on this in part 3):

1. Decreased activity
2. Poor dietary choices
3. Stress that leads to excess inflammation

We know that increased activity can have a huge impact on the other two factors mentioned. Thus, if we can keep active as we age, we will notice significant benefits, not only to our OA, but also our lives in general.

The fact of the matter is that Exercise will Improve all aspects of someone’s life. This improvement associated with exercise can be extrapolated to just about any condition, as well as any risk factor that is typically associated with negative outcomes (such as age).

What we tend to find is that people who come to see us, walk-in trying to resolve one issue (i.e. their knee pain) and walk out finding out they have resolved a whole host of other issues that they didn’t know they could solve. The key to all of this is exercise. And that’s why we’re so passionate about empowering everyone we work with to increase their levels of activity. It’s because when they do, they can start to avoid the curse of maladaptation associated with ageing, being able to live a happy and healthy life instead!

References

1. Is Long term physical Activity safe for older adults
2. Impact of Exercise on Articular Cartilage
3. What do People with Hip OA need to know
4. Running not worsening
5. Exercise, Inflammation & ageing
6. Age-related changes to the Musculoskeletal system
7. Physical activity & the effect on multimorbidity in older adults
8. Osteoarthritis Pathophysiology