Wear and Tear: Osteo-Arthritis |
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Joints move. The surfaces of the bones forming the joints run on each other. Eventually they wear each other down. Walk a mil and each hip moves a thousand times with your weight on it. A pianist may move a finger as many times in a few minutes. All the time the joints between your rinds and your spine are moving as you breathe, fifteen times or so a minute, which means nearly ten million times a year. Put another way -- some of your joints have moved as many times as the valves and pistons of a car that has gone 100,000 miles. The wonder is that our joints last as long as they do.
This wear and tear is taking place in all of us. It is worse in the joints that take the greatest strains, particularly the hips and knees. It is worse in joints subjected to unusual strains. The example usually given of this is the man who uses a pneumatic drill and wears out his wrist. Another example is a middle-aged woman who has a fall on to her hip; ten years later that hip begins to ache, showing that wear and tear in it has reached the stage where it is known as osteo-arthritis long before any other joints are seriously affected. Much commoner, though, is the man or woman who is too heavy and is wearing out the hips, kneed and ankles that have to support the excessive weight. If you want to keep your joints in good order take care, gentlemen, that your weight does not rise above what it was when you were twenty (this will allow you a little extra fat as your muscles diminish): ladies, we will allow one-half or at most one stone after the menopause, but no more. One woman may serve as extreme example of what can happen" she was carried into hospital weighing 18 stones; she walked out weighing 14 stones; all that had been done was to cut down the amount of food she are, even though, like so many fat people, she was not a big eater.
The strains and stresses to which a joint is subjected may wear down the smooth cartilage that covers the bearing surfaces of bones. Look at the joints in a piece of meat; each one is lined with white cartilage which can be shaved off with a carving knife and yet is smooth and tough. The nearest synthetic approach to it is solid nylon which is used in the gears of egg whisks, the gears of electric clicks, the springs of cars and a host other places because, like cartilage, it is tough and smooth. Good though cartilage is for the job it has to do, it is eventually worn down so that the bone that it covers is exposed. Injuries may even ship the cartilage off the bone and expose big areas of it. Bone is not as smooth as cartilage, so the joint no longer moves freely; the grating of rough surfaces over each other can easily be felt in a badly affected joint. The 'cartilages' of a knee, by the way, are two rings which are not attached directly bone and do not take the weight; this is taken by the ends of the bone which are covered with the same sort of cartilage as in other joints.
When the joint is damages, either by an accident or by the more gradual processes of wear and tear, it becomes inflamed; it becomes swollen and painful; it may even accumulate fluid like the lubricating fluid produced in every joint, but which is in far too great a quantity -- a so called "effusion" or "water on the knee". This it the 'acute' stage of osteo-arthritis which arises from time to time in an affected joint. Between times there is no inflammation but just a worn join which does not work as well as the original. When I say 'worn', please realize that I do not mean 'worn out'; a worn joint is capable of giving many years more service provided it is treated reasonably. I am reminded of the 1026 bus which is seen from time to time where I live; it is worn but not worn out; its owners would not consider putting it back into regular service but they will continue to use it for occasional outings for a long time to come.
The only joints which can really be said to be worn out are those few in which bone has been rubbing on bone for so long that the bones themselves are worn down. In these joints in which the osteo-arthritis has been severe there is an attempt by the bone to grow again but the results is a haphazard collection of knobs, known as osteophytes, around the edge of the joint, rather than a reconstruction of the original shape. These osteophytes eventually join up, in a process known as ankylosis, and prevent the joint moving at all, which does at least mean that it cannot hurt. The joints that are worn-out in osteo-arthritis are very few, however, compared with the many that just work a little less well than they did. The outlook in osteo-arthritis is always hopeful. |
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