A population study of 1,722 adults in Chenghai city, Guangdong province showed that the prevalence of osteoarthritis (OA) was 8.3% and there was no significant difference between male and female. The prevalence of OA increased after the age of 40 and reached a peak at 50-55 years. The prevalence of osteoporosis (OP) in OA patients of this population survey and in patients in our clinic was around 30%. OA accompanying OP was more frequently seen in female than male, especially in postmenopausal women. The results of CT screen of lumbar spine in 66 OA patients showed: 89.4% (59 cases) was associated with the protrusion of intervertebrale disc, occurring frequently at L4 and L5. MR imaging of 20 knee joints in 10 cases of OA patients with knee involvement showed: all of the patients were associated with one or all of the following conditions: chondropathies, degeneration or injury of semilunar plate, bursitis and synovitis. It is suggested that OA is a heterogeneous disorder and must be treated with different ways.