What Causes Arthritis?
Painful, debilitating and often life-changing, arthritis is something the knee surgeons of Yorkshire Knee Clinic treat virtually every day. But what is arthritis? Jim Newman explores the causes and explains why knee replacement remains the current best option for advanced osteoarthritis.
Although there are many different types of arthritis, most people are familiar with two: osteoarthritis (OA) is the most common, and the one most people associate with wear and tear. Then there’s rheumatoid arthritis (RA), the commonest form of inflammatory arthritis.
The two are quite different in the way they behave and present, and the causes are different, but ultimately, if left untreated, both may lead to the classic symptoms of joint pain, swelling and stiffness. Although surgery is now less common in cases of RA, both can require surgical intervention at some stage, the most obvious and common example being a knee replacement.
This piece focuses on osteoarthritis. You can find more about rheumatoid arthritis here.
What causes osteoarthritis?
There isn’t one single cause of OA so as knee surgeons, it’s not possible for us to say ‘avoid doing X and you won’t develop it’. OA is multifactorial, but we know some of the factors that can contribute to it include:
Genetics: OA does appear to run in families. We often see relatively young patients showing signs of OA and it’s very common to hear them say, “My dad had a knee replacement aged 60” or similar. We’re not clear what role genetics plays in triggering OA, nor do we know its effect relative to other factors, but there is clearly some genetic predisposition.
Trauma: A trauma that damages the gliding cartilage of the knee joint or the ligaments around it can be a major factor in the development of OA. That could be a car accident which damages the knee, but it could just as easily be a cruciate ligament injury – a bad injury in its own right, but which can also be the trigger for cartilage tears which may later lead to OA.
Medication: Some drugs may have an effect on OA, increasing the rate of progression by interfering with the normal healing processes of the knee. There’s lots of ongoing research in this area but currently we really don’t know to what extent medication is a factor.
Even if a drug was shown to worsen OA, the age old side effects debate then comes into play. Is it more important to avoid the OA, or to avoid the condition the drug is seeking to treat?
Wear and tear: For a condition often described as wear and tear-related, it might seem odd that it features last in this list of possible causes of OA, but the reality is we simply don’t know for sure that it is related to usage.
‘Wear and tear’ is often used as a sort of shorthand for the cause of OA because it tends to occur as people get older and we do see some level of degeneration of the joint. But is that degeneration a result of actual wear and tear (i.e. the work the knee has been asked to perform) or simply because all joints wear as they get older?
Wear and tear feels like a logical explanation but it doesn’t explain how, for every person we see with OA, there’s another who’s been a runner all their life and has no problem with their joints.
The most likely explanation at present is that the interrelation of factors is different in every person. If you’re a runner with no genetic predisposition to OA, you may be able to run your entire life with no degeneration. It’s possible that in some people that act of running can actually have a regenerative effect.
On the other hand, hammering your knee joints if you are genetically predisposed to OA, or if you’ve suffered some form of knee trauma, may make things considerably worse.
Why knee replacement is the current best solution for advanced OA
The arthritic process is a complex one. As a joint begins to wear out, the normal lubricant produced by the body begins to thin. As the knee tries to compensate it can grow additional bony spurs. The bones in the knee can become very solid in response to the increased pressure and forces placed through them. In advanced cases like these, much-hyped treatments such as stem cell therapy can’t really work because the knee is fundamentally changed from what it once was. Nor, despite the enormous amount of research in the area, can we currently regrow cartilage, not least because cartilage has no blood vessels to carry oxygenated blood cells to the damaged areas.
A partial or total knee replacement will never be a knee surgeon’s first option. Any surgical intervention inevitably involves greater risk than medication, physio and a change of lifestyle. But as it progresses and worsens, knee replacement remains the current best solution.
To explore options for your osteoarthritis, please get in touch.