Normal hip and knee active range of motion: the relationship to age.

Abnormal joint mobility is an important factor in movement dysfunction and physical disability. Because the decision to treat impaired joint mobility in an older individual may be influenced by assumptions concerning normal range of motion (ROM) at older ages, it is important to establish population-based normative values for hip and knee ROM by age, race, and sex. This study used data from the first National Health and Nutrition Examination Survey (NHANES 1), which involved a national probability sample of persons drawn from the civilian noninstitutionalized population of the United States. Goniometric measurements of hip and knee active range of motion (AROM) were obtained from a subset of the sample consisting of 1,892 subjects. This analysis was limited to the 1,313 white and 370 black subjects. Univariate statistics, weighted by the probability of selection into the sample, were calculated for 12 sex-race-age-group-specific categories. These normal AROM values for the hip and knee calculated from this population based sample were found to differ from estimates found in textbooks by as much as 18 degrees. With one exception, normal values for all motions were lower in the oldest age group than in the youngest age group. The differences in mean AROM were generally small, ranging from 3 to 5 degrees. Only in the case of hip extension did the difference in mean AROM between the youngest and the oldest age groups constitute a decline of more than 20% of the arc of motion. With the possible exception of hip extension, this study supports the conclusion that, at least to age 74 years, any substantial loss of joint mobility should be viewed as abnormal and not attributable to aging and therefore should be treated much as it would be in a younger individual.