ANKLE ARTHRITIS

To investigate the prevalence of osteoarthritis (OA) of the knee in elderly subjects, we studied the Framingham Heart Study cohort, a population-based group. During the eighteenth biennial examination, we evaluated the cohort members for OA of the knee by use of medical history, physical examination, and anteroposterior (standing) radiograph of the knees. Radiographs were obtained on 1,424 of the 1,805 subjects (79%). Their ages ranged from 63-94 years (mean 73). Radiographs were read by a radiologist who specializes in bone and joint radiology, and were graded 0-4 according to the scale described by Kellgren and Lawrence. OA was defined as grade 2 changes (definite osteophytes), or higher, in either knee. Radiographic evidence of OA increased with age, from 27% in subjects younger than age 70, to 44% in subjects age 80 or older. There was a slightly higher prevalence of radiographic changes of OA in women than in men (34% versus 31%); however, there was a significantly higher proportion of women with symptomatic disease (11% of all women versus 7% of all men; P = 0.003). The age-associated increase in OA was almost entirely the result of the marked age-associated increase in the incidence of OA in the women studied. This study extends current knowledge about OA of the knee to include elderly subjects, and shows that the prevalence of knee OA increases with age throughout the elderly years.

A modification of Cobey's method for radiographically imaging the coronal plane alignment of the hindfoot is described. Using this view, we estimated the moment arm between the weightbearing axis of the leg and the contact point of the heel. Normative data on 57 asymptomatic adult subjects are presented. The weightbearing line of the tibia falls within 8 mm of the lowest calcaneal point in 80% of subjects and within 15 mm of the lowest calcaneal point in 95% of subjects. The technique for measuring coronal plane hindfoot alignment is reliable, with an interobserver correlation coefficient of 0.97. This radiographic technique should help in the evaluation of complex hindfoot malalignments.

A carbon black transference technique was used to determine the contact area in twenty-three dissected tibiotalar articulations, with the talus in neutral position and displaced one, two, four, and six millimeters laterally. The greatest reduction in contact area occurred during the initial one millimeter of lateral displacement, the average reduction being 42 per cent. With further lateral displacement of the talus the contact area was progressively reduced but the rate of change for each increment of shift was less marked.