Age-related changes in the joint position sense of the human hand

Abstract

Age-related changes in lower limb joint position sense and their contributions to postural stability are well documented. In contrast, only a few studies have investigated the effect of age on proprioceptive hand function. Here, we introduce a novel test for measuring joint position sense in the fingers of the human hand. In a concurrent matching task, subjects had to detect volume differences between polystyrene balls grasped with their dominant (seven test stimuli: 126-505 cm(3)) and their nondominant hand (three reference stimuli: 210, 294, and 505 cm(3)). A total of 21 comparisons were performed to assess the number of errors, the weight of errors (ie, the volume difference between test and reference stimuli), and the direction of errors (ie, over- or underestimation of test stimulus). The test was applied to 45 healthy subjects aged 21 to 79 years. Our results revealed that all variables changed significantly with age, with the number of errors showing the strongest increase. We also assessed tactile acuity (two-point discrimination thresholds) and sensorimotor performance (pegboard performance) in a subset of subjects, but these scores did not correlate with joint position sense performance, indicating that the test reveals specific information about joint position sense that is not captured with pure sensory or motor tests. The average test-retest reliability assessed on 3 consecutive days was 0.8 (Cronbach's alpha). Our results demonstrate that this novel test reveals age-related decline in joint position sense acuity that is independent from sensorimotor performance.

Keywords: aging; hand functions; joint position sense.

Figures

Figure 1

Set of polystyrene balls used for the assessment of joint position sense. Notes: A set of seven polystyrene balls (126, 210, 252, 294, 337, 421, and 505 cm3) was used to quantify the performance of the joint position sense of the subjects. One ball was enclosed in each hand simultaneously to detect size differences. As the enclosure is a typical and highly stereotypical explorative procedure by which to gather information about an object’s volume,,, all calculations were carried out in units of cubic centimeters (cm3).

Figure 2

Joint position sense performance in the three subtests (large reference, mid-size reference, and small reference). The performance was assessed in young subjects (A), adult subjects (B), and older adults (C). Notes: There was no significant interaction of the factors “group” (young, mid-aged adults, older adults) and “session” (big reference, mid-size reference, small reference) in repeated measures ANOVA for the number of errors (F(4,84) = 0.666; P = 0.618), the weight of errors (F(4,84) = 0.073; P = 0.990), and the direction of errors (F(4,84) = 1.925; P = 0.114). Data is given as mean ± standard error for all age groups and subtests. The results of all subtests were summed up per group (sum). The variable weight of errors was adjusted to fit into the diagrams [cm3/10]. Abbreviation: ANOVA, analysis of variance.

Figure 3

Joint position sense performance across the lifespan. There was a significant age-related change across all variables acquired by the joint position sense test. The number of errors increased with age (N = 45; r = 0.543, P ≤ 0.001) (A) Similarly, the weight of errors increased with age (N = 45; r = 0.311, P = 0.038) (B). There was no significant difference in the average direction of errors between the subjects of the three age groups (N = 45; r = 0.072, P = 0.637), but the scatter of these data increased with age (N = 9 (ie, standard deviation obtained in the three subtests per age group); r = 0.543, P ≤ 0.001) (C). Note: Data is given as single subject data (blue diamonds) and mean for each age group (red squares).

Figure 4

Correlation-analyses of joint position sense parameters. We calculated significant correlations between the number of errors and both other parameters of the proprioceptive hand function test (weight of errors; partial correlation corrected for age; N = 45; r = 0.737; P ≤ 0.001 (A), and absolute value of direction of errors; partial correlation corrected for age; N = 45; r = 0.418; P = 0.005 (B)). Notes: The analyses were based on the summed values of the three subtests. Blue diamonds give individual data; red squares give mean ± SD.

Figure 5

Test–retest reliability of the joint position sense assessment. The test–retest reliability was investigated in a subset of 15 mid-aged subjects, who performed the joint position sense test on 3 consecutive days (day one (A); day two (B); day three (C)) within 1 week. Notes: All calculations were based on the summed data of the three subtests (sum). Test–retest reliability was acceptable for the number of errors (Cronbach’s alpha = 0.787) and the weight of errors (Cronbach’s alpha = 0.761); moreover, the reliability of the direction of errors was good (Cronbach’s alpha 0.833).