The purpose of this study was to clarify the influence of pain and radiographic findings of osteoarthritis (OA) of the knee on postural stability in rural-community-dwelling elderly persons.
A total of 314 participants, consisting of 98 men and 216 women, aged 55 to 83 years, were investigated. Subjects were classified into four groups according to the symptoms and radiographic findings: Normal; Pain (pain without radiographic OA); Asymptomatic OA (radiographic OA without pain); Symptomatic OA (pain with radiographic OA). Knee pain was defined as unilateral or bilateral pain of the knee that had persisted for more than 1 month. Radiographic OA was defined as grades 2-4 according to the Kellgren and Lawrence criteria. The movement of the center of pressure (COP) was measured using a force platform to quantify postural sway.
Among the men, subjects in the Asymptomatic and Symptomatic OA groups showed higher values of the envelopment area tracing by the movement of the COP (E AREA) and the distance of the movement of the COP per second (LNG/TIME) under closed-eyes condition. Among the women, subjects in the Asymptomatic and Symptomatic OA groups showed higher values of E AREA and LNG/TIME under both open- and closed-eyes conditions. In the regression models consisting of the variables pain and radiographic OA, all estimates for pain were less than zero in both sexes. The value was significant only on the E AREA under closed-eyes conditions in women. On the other hand, all estimates for radiographic OA were higher than zero for both sexes. These values were significant for E AREA and LNG/TIME under open-eyes conditions in women, and E AREA and LNG/TIME under closed-eyes conditions in both sexes.
Subjects with OA showed greater postural sway than those without it. Only radiographic OA was a significant factor for increasing postural sway.