28 Jun Rest or not Rest – Joint Related Pain
Written By Megan Hunter
How many times have people heard expressions like “bone on bone” or “wear and tear” when it comes to joint pain? We are all aware that the body changes as we age and we have concluded that wear and tear is the cause of our pain. Bone on bone must be bad right?
First, let us talk about cartilage. The thing you may be interested to know is that most of the cartilage in our joints (articular cartilage), does not have it’s own nerve supply and therefore it cannot create pain. So, when a scan talks about the articular cartilage being “degenerative” or it is described to you that it is “worn down” it is important to know that it is not that structure that is causing the pain. Further to that, when looking at an x-ray where it looks like there is “bone on bone” i.e. there is little to no “gap”/joint space between the bone of the thigh and the bone of the leg, it is very unlikely that there is absolutely no cartilage left in the knee.
Cartilage functions to cushion the joint so that loading forces are absorbed well and distributed more evenly rather than having one part of the joint taking load all the time. With changes in the cartilage due to injury or “joint health”, the cartilages ability to do this well can be impaired creating areas of the joint that have to cope with more load.
Articular cartilage also does not have a direct blood supply, so requires its nutrients to be delivered in another way. In a joint, cartilage is made up of cross-linked fibres with space for water molecules in between. Imagine a 3D grid of string with balloons in between. When load is applied to this network the water is “displaced” out of the way like the air moving in the balloons, creating a cushioning effect. However, this displacement of water also results in some movement of water out of the cartilage and into the fluid within the joint space. This is how the joint stays healthy. Waste product travels out of the cartilage in the water and then is absorbed into the joint capsule (the thin, ligament-like lining of the joint). The joint capsule has its own blood supply and therefore can remove the waste product through blood flow. The body can deliver nutrients via the same way – delivered from the blood, through the capsule, into the joint fluid and into the cartilage with this movement of water.
I may or may not have lost you – but the point is that a joint requires nutrients and can only achieve this through the displacement of water in and out of the cartilage, achieved with MOVEMENT of the joint. Rest is certainly not best if we want to improve joint health.