Arthrosis – most people imagine that this means that their joints are worn down. Like the brake pads on a car wearing down with time. However, the cartilage is not gradually worn down. Lubrication by the fluid in the joints is so perfect that, even at a great age, there is no wear and tear through friction. Even the joint cartilage itself shows no significant signs of aging. Nevertheless, in cases of arthrosis, there is damage to the joint cartilage. This damage is not distributed over the entire surface of the cartilage, but is found only on locally restricted areas. It is interesting that arthrosis almost always begins on areas of the cartilage which are subjected to less wear. So, if arthrosis is not caused by friction or load, then what is the cause?
There is one decisive factor which can damage cartilage: if the supply of nutrients to the cartilage (the metabolic process) is disrupted, the inner chemistry of the cartilage changes, it is no longer able to carry out the tasks for which it is intended and suffers damage.
How can the supply of nutrients to the cartilage be disrupted?
Cartilage contains no blood vessels or lymph vessels. Nutrients pass into the cartilage cells and waste products are transported away by diffusion and a pump mechanism which operates as follows: The inner membrane of the joint (inner layer of the joint capsule) is well-supplied with blood. It produces the synovial fluid which contains all the nutrients the cartilage requires. This is released into the joint fissure and is distributed evenly over the entire joint cartilage by the movement of the joints. From here the nutrients pass into the cartilage cells by diffusion in the same way as the waste products pass from the cartilage cells into the synovial fluid. The important feature is that this process is fundamentally supported by a pump mechanism functioning as follows:
Through alternating pressure and decompression on the joint cartilage caused by movement, the cartilage is first compressed and then fully saturated like a sponge. It can release waste products when under pressure and absorb nutrients when pressure is relieved. It is therefore obvious: alternating compression and decompression are decisive factors in a healthy supply of nutrients to the cartilage. Both permanent pressure as well as permanent lack of pressure lead to disturbances in the supply of nutrients. However, this is precisely what often occurs nowadays. Most of us sit too much or have other one-sided occupations. Many movements which are theoretically possible in our joints are never used in daily life. As a result, some areas of joint cartilage are subjected to too little alternating pressure and decompression and arthrosis therefore gradually occurs. The shortening of the muscles resulting from this makes the muscles much more susceptible to damage. An unaccustomed movement, which demands more tension from some muscle fibres and their accompanying fascia than they are accustomed to, forces a movement in the joint which deviates from the normal pattern of movements. This leads to increased shearing stress on the cartilage and causes damage.
When we speak of arthrosis pains, we usually presume that it is the damaged joint cartilage which hurts. However, cartilage itself does not contain nerve fibers. But the pain is really felt in the joint, isn´t it? Where can the pain come from then? In our opinion the sick muscles and their fascia described previously are often the cause. This also explains the frequently observed phenomenon that the extent of cartilage damage shown on the X-rays bears little relation to the degree of pain. There are patients with chronic cartilage damage who have relatively little pain and patients with little cartilage damage but severe pain. Arthrosis pains do not depend on the degree of cartilage damage, but on the amount of sick muscle fiber and fascia.