What Actually IS Osteoarthritis?

Osteo - bone, Arth - Joint, Itis - Inflammation. OR IS IT?

Hello there Rheumatology Fans,

What To Expect In This Article - A Lot Of Meandering!

• Introductory Thoughts (free)

• Weight and OA

• What Do I Think OA Is?

• Symptoms/Imaging

• Management

Introductory Thoughts

According to The World Health Organization, OA is one of the top 10 most disabling diseases It's estimated that 10% of men and 18% of women over the age of 60 have Osteoarthritis. Many many more will have radiological changes associated with Osteoarthritis.

Once upon a time, I, like many people, thought of Osteoarthritis (OA) as a simple problem. Much like the tyres of a car, the more your joints were used the more they would wear away. Sure, some people were more prone to this by either being unlucky that their genetics caused them to be that way or they were over-weight so they put more force through their joints and wore it out quicker.

The most common locations to get OA are the knee and the hip, which are overtly high-load joints. Bunions are a Hallux Valgus caused by OA of the first Metacarpal Phalangeal Joint, another known high-load area. This is a pervasive narrative. How many people have you heard over the years say the following?

“Running will wear out your knees”

“I played lots of sports when I was younger so I have arthritis now”

In fact, I ran my own little test and asked my family members (a hopefully biased subgroup) what they think causes Osteoarthritis...

Brother 1 - “Alien probes or, and this is a complete guess...cell mutations”

Brother 2 - “I imagine diet might be a cause? Not enough cartilage-producing vitamins and minerals...”

Sister-In-Law - “I'm assuming there are many causes...Is the cause of the pain a lack of cartilage between the bones so you end up with bone rubbing on bone? Erm... Diet? Hypermobility? Overuse (in terms of impact or something along those lines)?”

Sister - “I think it’s joint damage - injury, overuse, increased weight bearing due to obesity?”

Mum - “Wear and tear of the weight bearing joints”

This idea that joints have a shelf life or a certain amount of use in them before eventually rubbing away to inevitable bone-on-bone with the associated pain, stiffness and lack of range of motion seen in older people is common. It all makes intuitive sense: older people who have used their joints more than younger people get OA and, as the population grows steadily older on average, we are seeing more and more OA diagnosed.

There is also a clear mechanism for those who are overweight being more likely to get OA of course, because with each step more force goes through each joint which may hypothetically speed up the process of degeneration. We can use our car tyre idea again, in that if you carried lots of heavy things in the car you would expect the tyres to wear down faster.

These narratives have taken a bit of a hit in recent times with multiple studies showing a lack of correlation between imaging findings and pain, that runners have lower incidence of symptomatic OA than sedentary people and that obesity causes as much OA in the CarpoMetacarpal Joint as in the knee and hip joints leading to one editorial being brilliantly titled “obese people do not walk on their hands”

There are some fascinating quirks with regards to weight and as well.