First of all, there are certain subpopulations who have more risk factors for osteoarthritis than others. Women tend to develop more severe degenerative arthritis on X-ray than men as a group. They also tend to develop more osteoarthritis of the hands and knees. Second, there are ethnic differences in that Caucasian people develop osteoarthritis more commonly, but it is very uncommon in Asian or black populations. These differences are of a genetic nature rather than environmental (see Ref. 2, p. 29). Third, there is an age dependent increase of frequency of osteoarthritis, with symptoms getting symptomatic around age 45 and peaking at about age 65. However, there seems to be a plateau beyond the age of 70, perhaps because of less mobility.
There are other risks like obesity
In addition, there are biomechanical factors such as obesity, which is a clear risk factor for weight dependent joints like hips and knees. At the same time, malalignment problems such as genu valgus (knock-knees) or genu varus (bowleggedness) lead to the development of premature osteoarthritis of the knee.
There are some cases where deposits of calcium crystals, such as calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate(BCP), are deposited in joints.
Calcium pyrophosphate dehydrate deposits in joints
For one thing, CPPD deposits are often present in severe knee joint osteoarthritis in elderly women and if proven by joint aspiration may be the first sign that the person has pseudo gout. Certainly, if BCP is found, this explains a severe destructive form of osteoarthritis and this has been described in elderly women as the “Milwaukee shoulder” (Ref. 1, p. 465). Specifically, the BCP crystals cause the lining of the joint to release inflammatory prostaglandins and cells, which leads to joint destruction with subsequent shoulder dislocation and irregular calcification from pseudo gout. An MR image will show a large joint effusion, resorption and deformity of the humeral head, and also a complete rupture of the rotator cuff. It is extremely difficult for an orthopedic surgeon to return such a shoulder back to normal function.
Overconsumption of sugar and refined starchy foods
One of the newer findings in the literature about osteoarthritis is that overconsumption of sugar and refined starchy foods lead to hyperinsulinism, which starts an inflammatory process that involves not only cytokines in the blood that circulate around, but affects also all of the joints and synovial membranes causing osteoarthritis in the joints. In the hands it affects more the DIP joints (distal interphalangeal, end finger joints) and PIP joints (proximal interphalangeal joints, middle finger joints), but not the metaphalangeal joints (hand/finger joints) with which rheumatoid arthritis typically presents. Eventually the immune system produces antibodies against your own joint surfaces that result in the degenerative changes seen on X-rays.
References
1. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 52.
2. ABC of rheumatology, second edition, edited by Michael L. Snaith , M.D., BMJ Books, 1999.
3. EL Cain et al. Clin Sports Med 2001 Apr;20(2):321-342.
4. B. Sears: “Zone perfect meals in minutes”. Regan Books, Harper Collins, 1997.
5. Goldman: Cecil Textbook of Medicine, 21st ed.(©2000)W.B.Saunders
6. Ferri: Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.
7. Rakel: Conn’s Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier
