[Osteoarthritis of the knee joint: a field study].

To clarify the natural history of osteoarthritis of the knee joint, a field study of the knee joint was performed on the inhabitants of Matsudai Town, Niigata Prefecture in 1979 and 1986. The study included the same 979 individuals, involving 820 women and 159 men, aged between 40 and 65 years in 1986 as in 1979. Narrowing of the femoro-tibial joint space was found in 17.7% and 26.1% of the women, and in 5.3% and 12.0% of the men, in 1979 and 1986, respectively. The individuals without osteoarthritic change and those with subchondral sclerosis or osteophytes in the femoro-tibial joint space exhibited less progressive changes in symptoms and radiographic findings. On the other hand, many of those in whom the joint space was more than 50% narrowed compared with the contralateral joint space had persistent pain, suggesting that they were candidates for active treatment. There were about twice as many women as men with symptomatic osteoarthritis of the knee. A comparative study of a group of women with, and a group of women without, radiographic progression in arthritic changes, indicated that the factors correlated with worsening osteoarthritis of the knee included aging, obesity, varus deformity of the knee, severity of inflammation, and flexion contracture of the knee.