Arthritis: What Does It Actually Mean?
⌚️ read time: 4 minutes
Laurie loves running, and it’s always been something she’s enjoyed with friends. But over the past few months, she notices a nagging pain in her left knee that is particularly bad on running days. She doesn’t remember ever injuring it, making it all the more irritating that it’s holding her back. She even canceled her favorite Saturday park run with her running group this week.
To make matters worse, her knee is creaking and popping with pain every time she squats down to pick something up. She mentions her symptoms to her friends, and they all ask her if she has arthritis in that knee.
Arthritis.
It had never dawned on her before. She used to hear her dad complain about it all the time and has a vague idea that arthritis causes…inflammation in the knee? Or wait, did it cause…bone spurs? Time to ask Dr. Google…
Everybody talks about it and most will experience it at some point in their lives.
But what the heck is it? As the years go by, I continue to realize how much confusion circulates about this nearly ubiquitous ailment.
So if you've been too busy or too afraid to ask the obvious question, today’s your freebie session to understanding arthritis.
What Is Arthritis?
Arthritis is a condition that affects the joints of our bodies.
So let’s start by defining a joint. A joint is any place in the body where two bones come together. This is a fluid-filled space (blue below). A soft tissue structure known as the joint capsule (think of a thick water balloon material) keeps the fluid inside the joint and links the bones together.
Most of our joints exist in the limbs or spine, and movement through the joint is how we, well, move! Obvious examples of joints would include the elbow or knee.
Ok, now let’s level up a bit.
What isn’t shown in the above drawing is that the ends of the two adjoining bones are covered in a very smooth, soft cap made of a tissue called cartilage (shown now in pink below). Imagine a smooth surface like the cue ball in a game of billiards, but made of soft cushioned tissue like your ear or nose. This absolutely flawless surface, along with the lubricating joint fluid, enables smooth, gliding, pain-free motion of your joint.
Pink: Smooth, soft cartilage within a normal joint
This is why it doesn’t feel like your bones are slamming together when you run or, at least early in life, your knees don’t creak when you squat down to pick up a child.
Alright now here’s what you came for today.
Arthritis, simply put, is any process that results in the breakdown of that smooth cartilage layer at the end of the bone.
That’s it. Plain and simple.
Loss of cartilage from the end of a bone within the joint.
Lose the cartilage? Now you don’t have that smooth, gliding, pain-free motion. You instead have bumpy, grinding, and often painful motion.
Your smooth white billiard cue ball just turned into a pockmarked white golf ball (see drawing below).
Pink: Rough cartilage within an arthritic joint
Different Types of Arthritis
Now that we understand arthritis as the end result of a process, we can dive a little deeper.
There are many different causes that will lead to that similar end result. The three most common pathways are:
Osteoarthritis (aging)
Post-traumatic arthritis (an old injury)
Inflammatory arthritis (autoimmune disease)
Let’s break each of these terms down into actual English.
Osteoarthritis
Another term for osteoarthritis is degenerative arthritis.
Yikes. Nobody wants to hear that word.
Whether we want to admit it or not, this is a normal aging process. The cartilage at the ends of the bones wears down over time. As this happens, the former smooth cartilage surface turns bumpy and rough. The two rough surfaces rub together as you move, resulting in squeaking, creaking, pain, and inflammation.
Osteoarthritis is the most common type of arthritis — and also the one with which you are probably most familiar.
Post-traumatic Arthritis
Post-traumatic arthritis is arthritis that develops after an injury, typically a fracture, that involves the joint surface.
If you break a bone and that fracture cracks through the end of the bone through the cartilage and into the joint, it obviously follows that the smooth cartilage surface will be altered. Even 1 to 2 mm of disruption will significantly affect the smooth gliding surface of the joint.
This is actually why surgery is often recommended when you break a bone through the joint. Surgical realignment of the joint surface allows for the most optimal healing.
But sometimes the damage has been done, and even with perfect surgery, this injured joint will have a lifetime increased risk of arthritis. Not guaranteed arthritis, but an increased risk.
This subsequent rough joint surface causes pain and inflammation in the same way as osteoarthritis.
Inflammatory Arthritis
The final common type of arthritis I’ll briefly touch on is the broad category of ‘inflammatory arthritis.’
This type of arthritis is often the result of one of various autoimmune diseases. If you have an autoimmune disease, your own immune cells can mistakenly attack and destroy the cartilage cells in your joint. This again causes the same pattern of degradation that leads to an all-too-familiar cycle of inflammation and pain.
Within this category, there are many different types of inflammatory arthritis, some of the most common being rheumatoid arthritis, psoriatic arthritis, or gout.
Takeaways:
Arthritis is a catch-all term that simply means ‘loss of the smooth cartilage within a joint'
Loss of smooth cartilage at the ends of bones can lead to pain and inflammation in a joint
There are many ways our body can reach this same endpoint of arthritis, including aging, old injuries, or inflammatory diseases like rheumatoid arthritis
As you can see, the first step is to determine what exactly has caused your arthritis. The treatment for you will then depend on what your underlying cause is and which particular joint is affected.
Stay tuned, as we will have lots of ground to cover discussing various specific arthritides and their associated treatment options in future articles.
