A chartered physiotherapist’s view
By Paul Bolger. Nano Physiotherapy www.nanophysio.ie
We have all heard the term ‘wear & tear’. This term should, in my opinion (and the opinion of some world-leading physiotherapists), be replaced with ‘Wear & Repair’. Why? Because this better reflects the reality of what occurs as we go through our lives.
Yes, things do wear and become damaged along the way – but our body, being alive and constantly adapting, repairs itself as we go along. Let’s start to gain a better understanding of this by exploring our amazing joints.
Your Joints are Alive
A joint is a place where two or more bones meet. In my lovely drawing, you can see the joint is surrounded by a capsule – a robust, ligament-like structure that completely envelopes and seals the joint. Within this capsule is a reservoir of synovial fluid. You can think of synovial fluid like your body’s very own WD40 – but it is much more than simply a lubricant.
Synovial Fluid – A Living Liquid
Inside of your knee joint there is about a teaspoon of synovial fluid – this is more than enough to completely coat and protect the entire joint surface.
Synovial fluid is full of cells and molecules. Some of these cells and molecules promote trimming and tidying the joint (e.g. immune/ inflammatory cells), helping to clear any damage, however minor or major. Other cells promote healing and growth of the tissue within the joint (e.g. chondrocytes form cartilage).
This cycle of trimming and tidying (wear) and regrowth and renewal (repair) is an ever-present right through our lives. Issues might arise when this cycle is thrown out of whack – such as in rheumatoid arthritis and often in osteoarthritis.
Incredibly, the consistency of synovial fluid changes depending on the type of activity you are doing. When you are resting or gently moving, synovial fluid takes on the consistency of egg white – allowing free and easy motion. When you do a more impactful activity, such as walking or running, it becomes honey-like on impact – firmer, coating your joints and absorbing impact while reducing friction. As soon as the pressure of impact eases, synovial fluid becomes more free flowing again. Incredible!
Motion is Lotion
The cells and molecules within synovial fluid are replenished by blood – but there is no direct blood supply to the joint surface or the synovial fluid. The nutrients diffuse from blood vessels in the capsule, seep into the joint and filter through the synovial fluid to feed and nourish the joint tissues.
Movement aids this process – pumping and pushing the synovial fluid and massaging nutrients into the parts of the joint tissues.
One of these substances, lubricin, is nearly frictionless and is one of the most lubricating substances known in nature. Lubricin coats and protects our joint surfaces and is found throughout our body where motion takes place – such as in our eyes, between our organs and around our tendons.
There is a lot we can do besides just movement to take care of our joints and synovial fluid. Consider, for instance, the health and balance of our immune system – our main protective system.
We will explore this further in the coming weeks.
