Degenerative joint disease, or osteoarthritis, is the leading cause of disability in the United States, with some 27 million people affected.
To get more information on this disease, let’s start with some background.
Bones are covered by cartilage anywhere they rub against each other (joints). The end of a bone is kind of like a Tootsie-Pop, where the candy outside is cartilage and the Tootsie Roll center is the bone. Unfortunately, the cartilage is much thinner than the candy on a Tootsie Roll pop. This cartilage is slippery like a Teflon coating, and is what keeps the bones from rubbing together. As long as the cartilage is in good condition on both sides of the joint, there is no abnormal joint wear and no pain. Life is good.
Fast forward to age 65 and things are changing.
80 percent of 65 year olds have joint degeneration that is visible on an X-ray. One of the things that happens to cartilage as it ages is it becomes dehydrated. I guess drying out as you age is no great surprise. When cartilage dries out, it becomes less slippery and more fragile. Thus, relatively modest trauma that a young joint would tolerate can easily injure an older joint.
Degenerative arthritis is an outcome that is the common endpoint to a number of insults to joints.
There is clearly a hereditary side to this problem, with an estimated 60 percent of osteoarthritis inherited. Other causes of arthritis are due to damage to the joint, specifically damage to the cartilage covering the bone. Trauma to the joints through activities such as high velocity contact sports frequently results in joint injuries. This is common enough that people sometimes refer to an arthritic knee as a “football knee.”
Other causes of cartilage damage are infection or gout. Infection breaks down the cartilage and can do devastating joint damage. Gout causes uric acid crystals in the joint that work like sandpaper. Joints that have unusual stress on them are frequently damaged. This is the cause of osteoarthritis of the spine in someone with moderate scoliosis (curvature of the spine). Obesity also puts abnormal stress on joints sometimes causing premature failure.
What doesn’t cause joint damage is at least as interesting as what does.
Running for exercise doesn’t cause degenerative joint disease of the knees. Cracking your knuckles does not cause arthritis of the hands. Most researchers see no correlation between physical labor and osteoarthritis unless accompanied by joint injury.
So it seems more “use it or loose it” than “don’t wear it out.”
Prevention is all about maintaining the cartilage covering of bone in good condition. Picking your parents would be a good start. There is limited data that glucosamine, commonly available in vitamin stores, can rehydrate cartilage. This works pretty well on paper, but has not yet shown benefit in any big study. While we are talking magic supplements, I can say with complete confidence that chondroitin is absolutely no use to any joints; except the sharks.
So stay active, this has been shown to both lessen arthritis pain and slow down the damage. Keep yourself lean. Maybe add glucosamine to your vitamin list, and think twice about pursuing professional hockey or skydiving as a vocation.
I may be somewhat of an expert. I have 1,300 skydives – and the arthritis – to prove it.
Dr B (aka Don Bucklin).