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Reliability and Validity of Ankle Proprioceptive Measures Nandini Deshpande, MSc, PhD(c), Denise M. Connelly, PhD, Elsie G. Culham, PhD, Patrick A. Costigan, PhD ABSTRACT. Deshpande N, Connelly DM, Culham EG, Costigan PA. Reliability and validity of ankle proprioceptive measures. Arch Phys Med Rehabil 2003;84:883-9. Objective: To determine the reliability and validity of ankle proprioceptive measures. Design: Reliability was assessed between test occasions. Construct validity was addressed by the ability of measures to differentiate among groups. Setting: Laboratory of an educational institution. Participants: Eight healthy adults were recruited into each of 3 groups: (1) young (20 –39y), (2) middle-aged (40 –59y), and (3) older adults (ⱖ60y). Four subjects from each group (n⫽12) participated in retesting. Interventions: Not applicable. Main Outcome Measures: Threshold for perception of passive movement, error in active reproduction of position, error in reproduction of velocity, and error in reproduction of torque. Results: Intersession reliability was excellent (intraclass correlation coefficient [ICC] range, .79 –.95) for threshold for perception of movement, error in active reproduction, error in velocity reproduction, and error in dorsiflexion torque reproduction; intersession reliability was good for error in reproduction of plantarflexion torque (ICC⫽.72). Threshold for perception of movement differed between groups 1 and 3 and between groups 2 and 3 (P⬍.05). Error in reproduction of position was greater in group 2 than in group 1 (P⬍.05). Conclusion: Differences in proprioception between the older and the 2 younger groups were best detected by using threshold for perception of passive movement. Key Words: Aging; Ankle; Proprioception; Rehabilitation; Reproducibility of results. © 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation HE VISUAL, VESTIBULAR, and somatosensory systems convey information about limb and body movement, force, T pressure, tension, and movement in space that is needed for motor control.1,2 The somatosensory system is responsible for the manifestation of proprioception, defined as the perception of awareness of joint position and motion.2 The receptors for these sensations are mechanoreceptors located in joint capsule, ligaments, menisci, musculotendinous unit, and in the skin.2,3 Impairment in proprioception has been linked to increased age,4-6 ligament injury,7,8 peripheral neuropathy,9,10 multiple
From the Department of Kinesiology, University of Waterloo, Waterloo (Deshpande); and Schools of Rehabilitation Therapy (Connelly, Culham) and of Physical and Health Education (Costigan), Queen’s University, Kingston, ON, Canada. Presented in part at the Aging and Technology Conference, September 2001, Toronto, ON. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Elsie G. Culham, PhD, Sch of Rehabilitation Therapy, Queen’s University, Kingston, ON K7L 3N6, Canada, e-mail:
[email protected]. 0003-9993/03/8406-7473$30.00/0 doi:10.1016/S0003-9993(03)00016-9
sclerosis,11 and osteoarthritis.2,4 Proprioception is likely to be affected early in the disease process, because it is a complex system that requires integration of sensory input from many receptors.12 Objective quantification of proprioception may improve early detection of proprioceptive loss and help quantify this loss with aging. Rehabilitation programs are advocated to improve proprioception8,13-15; however, there is little evidence that proprioception can be improved by exercise.16 Difficulty in detecting minimal, but potentially important, alterations in proprioception may be partly because of the lack of reliable and valid methods of quantifying joint position and movement sense. Present methods of proprioception quantification predominantly involve measurement of kinesthesia (ability to detect movement) and joint position sense (JPS). A common measure of kinesthesia is the threshold for perception of slow passive movement (⬍1°/s). JPS is assessed by determining the error associated with active or passive reproduction of a joint angle.5,17-20 Musculotendinous receptors also play an important role in the perception of speed of movement as well as force production. However, evidence regarding the perception and reproduction of movement velocity is not readily available. In addition, although psychophysical studies have assessed the sense of effort or ability to reproduce muscle force,21 no evidence could be cited for the assessment of reproduction of muscle force under the paradigm of proprioception quantification or the alteration in this ability with normal aging. Controlling movement velocity and muscle force are important in protective responses,22,23 especially as an individual ages. The purpose of this study was to assess the reliability and construct validity of 4 proprioceptive measures. Threshold for the perception of passive movement and active-to-active reproduction of joint position are established proprioceptive measures, whereas the reproduction of movement velocity and torque are new tests, which were added to measure aspects of proprioception not addressed previously. It was hypothesized that threshold for perception of passive movement would be greater in older adults and that error in reproduction of position, velocity, and muscle force would be greater in older adults secondary to age-related impairment in proprioceptive input. The ankle joint was selected for the assessment of proprioception in this study because of its predominant role in postural control.24 METHODS Participants Group 1 was young adults (20 –39y), group 2 was middleaged adults (40 –59y), and group 3 was older adults (ⱖ60y). Subjects were excluded if they had a history of pathology of either the ankle or the subtalar joint, restricted right ankle range of motion (ROM) of less than 20° of dorsiflexion or 30° of plantarflexion, severe arthritis of lower-extremity joints, or symptoms of central or peripheral nervous system dysfunction. None of the subjects had diabetes. Older adults with a history of falling within the last 2 years or a Mini-Mental State Examination25 (MMSE) score of less than 29 of 30 were also excluded from participation. The MMSE was used to assess cognitive function in adults 70 years and older, because poor Arch Phys Med Rehabil Vol 84, June 2003
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cognition might have influenced their ability to follow instructions.20 Eight subjects were recruited in each of the 3 groups (N⫽24), based on a sample size calculation performed by using a measure of error in reproduction of joint position.20 Subjects were recruited from the university population and from the community and provided informed consent. The study was approved by the university human research ethics board. Construct validity26 of the proprioceptive measures was assessed by a test’s ability to discriminate among the 3 study groups. Reliability data were collected from 4 subjects in each group who agreed to participate in retesting within a 2-week period (n⫽12). Testing Protocol Threshold for perception of passive movement. Subjects stood with their right foot on a footplate attached to a torque motora (fig 1). The footplate’s axis of rotation was aligned with the lateral malleolus. The other foot was placed on a stable platform at the same height as the footplate and subjects were instructed to stand with equal weight on both feet. Support was provided by a backrest with Velcro® belts at the waist, hip, knee, and foot levels. The subjects closed their eyes during testing to eliminate visual input. From the neutral ankle position, the torque motor rotated the footplate at .25°/s, 3 times in a dorsiflexion and 3 times in a plantarflexion direction, in random order. The subjects pressed a switch when they perceived ankle joint movement and its direction. The angular
Fig 1. Subject positioning for threshold to perception of passive movement, reproduction of joint position, and velocity test. Arrow indicates position of potentiometer.
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displacement of the footplate required for perception of movement was recorded in degrees. Active-to-active reproduction of joint position. Subject positioning was as described above (fig 1). The subject’s ability to actively reproduce ankle joint position was tested once in each of 3 positions (5° of plantarflexion, 10° of plantarflexion, 5° of dorsiflexion) in random order. These positions were selected to avoid the extremes of the ROM to minimize additional sensory input from cutaneous receptors.27 From a neutral start position, subjects actively moved their ankle through their available ROM (beginning in either direction) at a self-selected speed and then stopped at 1 of the 3 test positions on the experimenter’s instructions. They concentrated on this position for 5 seconds and then moved the ankle through full range and back to the start position. Subjects were then asked to reproduce the test position actively; data were collected after subjects indicated that they had reproduced the position. Although subjects were asked to maintain equal-weight distribution, it is probable that most weight was taken on the left lower extremity during the task. The footplate’s displacement was recorded at 1000Hz for 3 seconds by using an attached potentiometer (standard error⫽.04°). The absolute difference between the test and the reproduced position was recorded. Reproduction of movement velocity. The subject stood as described earlier (fig 1); however, because of the nature of the task, it is likely that body weight was predominantly supported by the left lower limb during the testing. The footplate was mechanically restricted to allow movement between 20° of dorsiflexion and 22° of plantarflexion, to achieve a pain-free, comfortable, and consistent ROM for all subjects. Subjects moved the ankle joint through the available ROM at a selfselected velocity and then back to the starting position, while concentrating on the speed of movement. Self-selection allowed participants to choose a velocity they could perform smoothly and comfortably. After a pause of 5 seconds, they were asked to reproduce the same movement at the same velocity. The movement was started 3 times from 20° of dorsiflexion and 3 times from 22° of plantarflexion in random order. An average velocity was calculated for the dorsiflexion direction when starting in plantarflexion and for the plantarflexion direction when starting from dorsiflexion. The data from the potentiometer were collected at a sampling rate of 1000Hz. The average velocity was calculated from the middle one third of the movement, in an attempt to isolate the constant velocity portion of the movement. The outcome measure was the absolute difference between the test velocity and the corresponding reproduced velocity. Reproduction of torque. The isometric program of an isokinetic dynamometerb was used to assess torque reproduction. The subject was seated with a backrest angle of 100° and the knee in 60° of flexion. The right foot was positioned on the footplate, with the ankle joint in neutral and the axis of rotation of the dynamometer aligned with the lateral malleolus. The subject was stabilized by using straps across the hips, knee, and ankle. Maximum voluntary isometric torque of the dorsiflexor and plantarflexor muscles was obtained for descriptive purposes and to ensure that the test torque of 10Nm did not exceed 50% of the maximum voluntary isometric torque of the dorsiflexor or plantarflexor muscles. This precaution was taken to minimize fatigue caused by repeated torque production during testing. Subjects produced the test torque initially with verbal feedback from the investigator and then were asked to reproduce the same torque without feedback. Verbal feedback was chosen over visual feedback from the computer monitor to allow the subjects to concentrate on force perception rather than its visual
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representation. Subjects pressed downward on the footplate 3 times to produce 10Nm torque in plantarflexion and pulled up 3 times to produce 10Nm torque in dorsiflexion. The blocks of plantarflexion and dorsiflexion trials were introduced in random order. The test torque was maintained for 10 seconds, followed by a 5-second rest. Subjects were then asked to reproduce the same torque (3 trials in each direction) and maintain it for 10 seconds without feedback. A 1-minute rest period was provided between trials. Torque data were sampled at 100Hz. The mean torque was calculated from the middle 3.5 seconds of data for each trial in an attempt to ensure that the subject had reached a constant torque level. The outcome measure was the difference between the test and reproduced torque. Procedure Subjects were instructed to avoid physical activity immediately before the test session, to minimize fatigue during testing. A medical history, clinical examination, and the MMSE (subjects ⱖ70y) were completed to ensure that subjects met the inclusion and exclusion criteria. Ten-meter gait speed was measured for descriptive purposes and to compare the functional status of the subjects in the 3 groups. The subjects were timed over the middle 10m of a 15-m walkway at their selfselected speed. This procedure was repeated 3 times, and the average speed in meters per second was calculated. Tests were performed in the following order: (1) reproduction of joint position, (2) reproduction of velocity, (3) threshold for perception of passive movement, (4) isometric maximal voluntary contraction (MVC), and (5) reproduction of torque. The test order was chosen to minimize position change and to reduce total test time. Because the torque motor interfered with the accuracy of the potentiometer, position and velocity reproduction were measured before threshold for perception of passive movement. The position reproduction test preceded velocity reproduction, because it was easier for subjects to understand and it facilitated understanding of the velocitymatching concept. A practice trial was given before each test. Subjects wore flat-heeled shoes during test procedures. All data collection was completed by 1 tester, and procedures and subject instructions were consistent. Data Analysis Preliminary analysis revealed that threshold for perception of passive movement was not dependent on the direction of movement (paired t test, P⬎.05; N⫽24). Therefore, the angular displacement required for the subjects to perceive movement was averaged over the 6 displacements (3 dorsiflexion, 3 plantarflexion). Similarly, because error in reproduction of position was not dependent on test angle (analysis of variance
[ANOVA], P⬎.05; N⫽24), data from the 3 positions (5° of dorsiflexion, 5° of plantarflexion, 10° of plantarflexion) were averaged. The difference between the test and reproduced velocity was averaged over the 6 trials (3 dorsiflexion, 3 plantarflexion), because error in reproduction of velocity was not dependent on start position (paired t test, P⬎.05; N⫽24). Because error in reproduction of torque was greater for dorsiflexion than for plantarflexion (paired t test, P⬍.05; N⫽24), data were analyzed separately. Intraclass correlation coefficients (ICC2,k) were calculated (SPSS, version 10c) to determine the test-retest reliability.26 Construct validity was determined by the ability of the measures to discriminate among the 3 groups. Between-group differences were determined by using a univariate ANOVA (Sigmastat, version 2c), and the Tukey post hoc test was applied for between-group comparisons if an overall F value was significant (critical level, P⬍.05). RESULTS Sample Summary statistics for age, gender, height, weight, timed 10-m gait speed, and MVC are found in table 1. There were no differences between the 3 groups with respect to weight and gait speed. Gender distribution, height, and dorsiflexor and plantarflexor muscle MVC differed between the groups (P⬍.05). Reliability The mean age ⫾ standard deviation (SD) of the 12 subjects (8 women, 4 men) was 49.58⫾17.03 years. The mean weight and height were 67.48⫾12.99kg and 168.42⫾13.13cm, respectively. Mean age, height, and weight of the subjects participating in this phase of the study did not differ from their cohort or from the entire group of 24 subjects. Test-retest reliability of threshold for perception of passive movement, error in reproduction of position, error in reproduction of movement velocity, and error in dorsiflexion torque reproduction were excellent,28 with ICCs ranging from .79 to .95 (table 2). Reliability of plantarflexion torque reproduction was good28 (ICC⫽.72). Construct Validity Figure 2 displays the means and SDs of the 4 proprioceptive measures for the 3 groups. Differences were observed between the 3 groups for threshold for perception of passive movement. Post hoc analysis indicated differences between groups 1 and 3 and between groups 2 and 3, but not between groups 1 and 2. Differences were observed only between groups 1 and 2 for error in reproduction of joint position.
Table 1: Subject Characteristics Variable
Group 1 (n⫽8; 5 men)
Group 2 (n⫽8; 3 men)
Group 3 (n⫽8; 1 man)
P Value
Age (y) Weight (kg) Height (cm) Gait speed (m/s) MVC of DF (Nm) MVC of PF (Nm)
30.50⫾5.33 70.70⫾14.50 173.7⫾11.5 1.43⫾0.28 36.13⫾9.42 76.74⫾21.67
50.13⫾6.71 73.82⫾14.55 170.9⫾7.4 1.25⫾0.15 27.15⫾9.04 51.5⫾19.41
69.75⫾5.19 62.44⫾4.22 159.6⫾5.5 1.26⫾0.14 20.57⫾2.77 44.52⫾10.9
.000* .210 .014* .231 .002* .004*
NOTE. Values are mean ⫾ standard deviation. Abbreviations: DF, dorsiflexor muscles; PF, plantarflexor muscles. * Significant at P⬍.05.
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ANKLE PROPRIOCEPTIVE MEASURES, Deshpande Table 2: ICC2,k for the 4 Measures of Proprioception (nⴝ12) Measure
Day 1 (mean ⫾ SD)
Day 2 (mean ⫾ SD)
ICC2,k
Threshold for perception of passive movement (°) Error in reproduction of position (°) Error in reproduction of velocity (°/s) Error in reproduction of dorsiflexion torque (Nm) Error in reproduction of plantarflexion torque (Nm)
0.52⫾0.27 2.34⫾1.05 1.30⫾0.47 1.97⫾1.45 1.58⫾1.08
0.49⫾0.23 2.33⫾1.25 1.03⫾0.50 2.06⫾1.59 1.40⫾0.68
.95 .83 .79 .86 .72
No differences were observed among the 3 groups for error in reproduction of movement velocity. Subjects’ self-selected velocity ranged from 2.56° to 9.57°/s. The mean values were 5.89°⫾1.82°/s, 4.76°⫾2.27°/s, and 5.56°⫾2.74°/s for groups 1, 2, and 3, respectively, and there was no difference between groups (P⬎.05). The effect size was determined by calculating 2.29 Estimation of 2 showed a small effect size (2⫽.01) for age as an independent variable. No significant differences were observed between the 3 groups for error in reproduction of either dorsiflexion or plantarflexion torque. Power analysis (power⫽.80) established that 22 and 28 subjects would be required per age group to detect a difference in error in dorsiflexion and plantarflexion torque reproduction, respectively. DISCUSSION Reliability All proprioceptive tests showed good to excellent reliability. The threshold for the perception of passive movement is a
frequently used quantitative measure of proprioception at the ankle joint.9,10,19,30 Simoneau et al9 reported excellent reliability for this test when the second test session was completed within a few minutes of initial testing. No other evidence could be found for reliability of this measure. The excellent reliability found in this study shows the stability of this measure over a longer time period. Current results for active-to-active reproduction of joint position are consistent with the literature. Petrella et al20 observed a high test-retest reliability (r⫽.88) for active-to-active reproduction of knee joint position. Similarly, Gross31 showed high reliability (r⫽.99) for this test at the subtalar joint. The results of this study suggest that this test is reliable for assessing position sense at the ankle joint when the position is maintained actively during standing. The protocols were newly developed for the tests of reproduction of velocity and reproduction of muscle torque, and, therefore, no comparison data were available. The good to excellent reliability of these measures indicates that they may be useful in future studies for providing additional information
Fig 2. Mean error ⴞ SD for the young (group 1), middle (group 2), and older (group 3) subject groups for measures of ankle proprioception. (A) Threshold for perception of passive movement for group 1, .39ⴞ.06; for group 2, .57ⴞ.22; and for group 3, .92ⴞ.49 (Fⴝ5.98, Pⴝ.009). (B) Absolute error in reproduction of position for group 1, 1.61ⴞ0.40; for group 2, 3.03ⴞ1.31; and for group 3, 2.33ⴞ0.92 (Fⴝ4.48, Pⴝ.023). (C) Absolute error in velocity reproduction for group 1, 1.43ⴞ0.73; for group 2, 0.98ⴞ0.49; and for group 3, 1.27ⴞ0.59 (Fⴝ1.11, Pⴝ.348). (D) Absolute error in torque reproduction for dorsiflexion for group 1, 1.73ⴞ0.97; for group 2, 1.86ⴞ1.30; and for group 3, 2.93ⴞ1.63 (Fⴝ1.57, Pⴝ.244); and for plantarflexion for group 1, 1.56ⴞ0.86; for group 2, 1.27ⴞ0.79; and for group 3, 2.11ⴞ1.21 (Fⴝ1.596, Pⴝ.237). *Significant difference compared with group 1 and group 2 (P<.05). †Significant difference compared with group 1 (P<.05).
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regarding the dynamic aspects of proprioception as well as the ability to perceive and reproduce muscle force. Construct Validity The threshold for the perception of passive movement has been found to be sensitive to age-related deterioration in proprioception at the knee as well as the ankle joint.6,30 However, other studies have included only young and older subjects, resulting in a paucity of data for the healthy middle-aged population. Current results indicate that the test of threshold for perception of passive movement can detect differences between middle-aged and older adults as well. This test was the most useful of the measures studied for detection of age-related deterioration in proprioception. Timed 10-m gait speed test is a valid measure of functional status of older adults.32 No differences in speed were found among the groups, suggesting that the deficit in threshold to perception of passive movement observed in the older adults did not influence gait. Subjects were not tested for more demanding functional tasks, such as ability to recover from a perturbation or timed maximum gait speed. Further investigation in different populations, such as older adults with a fear of falling, may yield a threshold value of this deficit that may explain deterioration in simple functional tasks. Active-to-active reproduction of static position sense differed only between the young and the middle-aged groups. Previous research has shown that the active-to-active test for reproduction of joint position was able to detect age-related changes in knee joint proprioception. Petrella et al20 showed significantly higher (P⬍.001) error in knee joint reproduction during standing in active older adults as compared with young adults. Similarly, Hurley et al5 established significant agerelated deterioration (P⬍.001) in non–weight-bearing knee joints. The effect size may be larger at the knee joint than at the ankle joint because of neurophysiologic differences in sensory function of the 2 joints. Researchers have found that error in active-to-active reproduction of joint position is influenced by activity level. Petrella’s cross-sectional study found20 less (P⬍.03) error in active-to-active reproduction of knee joint position in physically active compared with sedentary older adults. Similarly, Bernauer et al,33 in a longitudinal study, showed significant improvement in position sense at the knee joint in healthy young subjects after an exercise program. The older adults in the current study were recruited primarily from 2 community clubs promoting recreational physical activity. It is possible that the activity level of this group was higher than would be found in the general older population which would contribute to the lack of significant findings for this measure. Gait speed, a reliable measure of functional ability in older adults,32 did not differ between the groups, which suggests that the older adults in this study had a high functional status. Error in active reproduction of velocity, a new test of kinesthesia introduced in this study, did not differ between groups. There are several possible explanations for this finding. First, this test was reported to be the most difficult test to perform by the subjects, because of the extensive concentration period (⬎12s) required during both the test movement and the reproduction of the movement. Second, the subject was bearing body weight primarily on the left lower limb during this test. Although no subjects complained of pain or fatigue, mild discomfort was reported by most subjects. This may have been distracting, leading to an increase in random error during velocity matching. Third, subjects were asked to concentrate on the complete movement and were not informed about the movement direction for which the data were collected. How-
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ever, data were collected only during the initial phase of movement, not the return phase, and it is possible that some subjects concentrated more on the return phase of the movement, leading to an increase in error. During pilot testing a decision was made not to inform subjects about this partial data collection, to simplify test instructions. Sense of effort or force is an additional aspect of proprioception that is not adequately tested using measures of joint position sense or kinesthesia.34 In the current study, lower errors were observed during reproduction of plantarflexion torque. Sensory input from plantar cutaneous receptors, in addition to information from plantarflexor musculotendinous receptors, might have resulted in better ability to perceive forces required for torque reproduction. There were no differences in dorsiflexor and plantarflexor torque reproduction error between the groups. The small sample size may have contributed to this finding; a power analysis indicated that 22 and 28 subjects were needed per group to detect a group difference in dorsiflexion and plantarflexion reproduction, respectively. This indicates that sense of force may be impaired in older subjects, but that the measure developed for this study was less sensitive to differences than the measures of JPS and kinesthesia. A constant test torque of 10Nm, irrespective of the subject’s MVC, was used as a test torque for all the subjects to attain standardization in the error calculation. However, psychophysical data suggest that the ability to match muscle force varies as a function of the magnitude of the force expressed as a percentage of a subject’s MVC. Lesser forces (up to 30% MVC) are overestimated, whereas higher forces (⬎70% MVC) are underestimated.21 The MVC values of the 3 age groups in this study differed for dorsiflexors as well as for plantarflexors (P⫽.002, P⫽.004, respectively), resulting in a variable test torque when calculated in terms of percent of MVC. The test torque of 10Nm was 27%, 37%, and 49% of the average dorsiflexor MVC for young, middle-aged, and older adults, respectively. The corresponding values for plantarflexion were 13%, 19.4%, and 22%. Although no evidence could be cited for the ankle muscle torque replication, it is possible that this variability differentially affected the ability to sequentially match the test torque. The higher MVC percentages used by the older adults may have been easier to match than the lower percentages used by the young subjects and may have offset the age-related deterioration. Study limitations included recruitment of the older participants primarily from 2 community clubs promoting recreational physical activity. Regular physical activity is known to slow significantly the age-related deterioration in many physiologic processes. The comparable gait speeds between the older and the young adults suggest a high functional status in these older adults. The unequal gender distribution in the groups contributed to differences in height as well as plantarflexor and dorsiflexor muscle MVC. However, subject recruitment was not guided by gender because no gender differences in proprioception have been found in either young or older adults.4,35 Only 1 method of measuring joint position sense was assessed in this study. Other methods include passive setting of an index angle and active reproduction,36 passive-to-passive reproduction,37 matching with the opposite limb (actively or passively),10 and use of a visual analog representation of the limb.4,38 There is little correlation between various measures of JPS or between measures of JPS and kinesthesia, which suggests that these tests measure different aspects of proprioception.39 It is argued that active-to-active reproduction uses both a sense of effort and a sense of joint position and, therefore, may result in more accurate matching of an angle compared Arch Phys Med Rehabil Vol 84, June 2003
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with a passive-to-passive reproduction test.40 Different receptors may also be involved in the passive versus the active reproduction tests. Anesthetic block of the ankle joint resulted in significant impairment in passive-to-passive reproduction (2°/s) of joint angle but did not affect active-to-active angle replication (approximately 15°/s).19 This finding suggests that joint receptors are involved in perception of slow passive movement. Active-to-active reproduction of joint angle may also use central processes—for example, memory of the motor task, as well as peripheral feedback. Ashton-Miller et al16 suggest that the effect of exercise programs on proprioception can be determined only by using a proprioceptive measure that does not involve a motor task. Impairment in the peripheral proprioceptive system, therefore, might better be assessed by using a passive-to-passive reproduction test. Similarly, a passive-to-active test of reproduction of velocity might be more sensitive to age-related changes in the peripheral system for the same reasons. Further research is needed to determine the relationship between various tests of joint position sense at the ankle and which would be the most appropriate to monitor change in proprioception with aging. CONCLUSION Threshold for perception of passive movement was found to be the most reliable and valid method of assessing age-related deterioration of proprioception at the ankle joint. This test, therefore, may be most useful for detecting subtle proprioceptive impairment and for monitoring changes in proprioception related to age or disease. Error in active-to-active reproduction of ankle joint position was greater in group 2 than in group 1. Research has suggested that this measure is influenced by regular physical activity, and, therefore, this test may be useful for assessing the efficacy of various exercise programs used for proprioception retraining. However, age-related changes in this measure and the effect of training on various measures of proprioception require further study. The unique aspects of this study include an attempt to quantify the dynamic aspect of proprioception and its deterioration due to normal aging. Similarly, the ability to perceive muscle force as well as the deterioration of this ability, because of normal aging, was assessed. The differences detected between the 3 age groups did not reach a level of statistical significance, which suggests the necessity for further refinement of these measures. Assessment of these aspects of proprioception may be of functional importance because of their role in protective responses, particularly during physically demanding situations. Therefore, further investigation of these measures will be important primarily for detecting impairment in at-risk populations, such as elderly fallers or those older adults who have a fear of falling. References 1. Diener HC, Dichgans J. On the role of vestibular, visual and somatosensory information for dynamic postural control in humans. Prog Brain Res 1988;76:253-62. 2. Lephart SM, Pincivero DM, Rozzi SL. Proprioception of the ankle and knee. Sports Med 1998;25:149-55. 3. Kavounoudias A, Roll R, Roll JP. Foot sole and ankle inputs contribute jointly to human erect posture regulation. J Physiol 2001;532:869-78. 4. Barrett DS, Cobb AG, Bentley G. Joint proprioception in normal, osteoarthritic and replaced knees. J Bone Joint Surg Br 1991;73: 53-6. 5. Hurley MV, Rees J, Newham DJ. Quadriceps function, proprioceptive acuity and functional performance in healthy young, middle-aged and elderly subjects. Age Ageing 1998;27:55-62. Arch Phys Med Rehabil Vol 84, June 2003
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31. Gross MT. Effects of recurrent lateral ankle sprains on active and passive judgements of joint position. Phys Ther 1987;67:1505-9. 32. Potter JM, Evans AL, Duncan G. Gait speed and activities of daily living function in geriatric patients. Arch Phys Med Rehabil 1995;76:997-9. 33. Bernauer EM, Walby WF, Ertl AC, Dempster PT, Bond M, Greenleaf JE. Knee-joint proprioception during 30-day 6 degrees head-down bed rest with isotonic and isokinetic exercise training. Aviat Space Environ Med 1994;65:1110-5. 34. Fleury M, Bard C, Teasdale N, et al. Weight judgment: the discrimination capacity of a deafferented subject. Brain 1995;118: 1149-56. 35. Gilsing MG, Van den Bosch CG, Lee SG, et al. Association of age with the threshold for detecting ankle inversion and eversion in upright stance. Age Ageing 1995;24:58-66. 36. Konradsen L, Magnusson P. Increased inversion angle replication error in functional ankle instability. Knee Surg Sports Traumatol Arthrose 2000;8:246-51. 37. Bernier JN, Perrin DH. Effect of coordination training on proprioception of the functionally unstable ankle. J Orthop Sports Phys Ther 1998;27:264-75.
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38. Roberts D, Friden T, Zatterstrom R, Lindstrand A, Moritz U. Proprioception in people with anterior cruciate ligament-deficient knees: comparison of symptomatic and asymptomatic patients. J Orthop Sports Phys Ther 1999;29:587-94. 39. Grob K, Juster M, Higgins S, Lloyd D, Yata H. Lack of correlation between different measurements of proprioception in the knee. J Bone Joint Surg Br 2002;84:614-8. 40. Beynnon BD, Renstrom PA, Konradsen L, Elmqvist LG, Gottlieb D, Dirks M. Validation of techniques to measure knee proprioception. In: Lephart SM, Fu FH, editors. Proprioception and neuromuscular control in joint stability. Pittsburgh: Human Kinetics; 2000. p 127-38. Suppliers a. Compumotor®, model 605; Parker Hannifin Corp, Compumotor Div, 5500 Business Park Dr, Rohnert Park, CA 94928. b. Biodex System 3®; Biodex Medical, 20 Ramsay Rd, PO Box 702, Shirley, NY 11967-0702. c. SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL 60606.
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