Osteoarthritis can be classified into two major categories: Primary OA and Secondary OA. Primary OA lacks a specific cause such as trauma or disease. Secondary OA is caused by trauma or some known abnormality such as an infectious disease or endocrine disorder.

A recent study examined the long-term benefits of exercise in osteoarthritis patients. Of the 201 individuals that started the study, 183 completed it. Patients involved suffered from OA of the knee or hip. Follow up on the patients in the study was conducted at 6 and 9 months. The two intervention groups, the control group and the exercise group, received doctor's care, and drug therapy if necessary. The experimental group was also engaged in an exercise program for 12 weeks with a physiotherapist as a coordinator of the exercise therapy. The outcome measurements consisted of pain, drug use, and disability. A small to moderate decrease in pain was observed at the 24-week period, but at week 36, there was no difference in pain between the two groups. The researchers discovered that in OA sufferers, exercise benefits decline over time and eventually disappear.²