The correlation between postural control and upper limb position sense in people with chronic ankle instability
Springer et al. Journal of Foot and Ankle Research
The correlation between postural control and upper limb position sense in people with chronic ankle instability
Shmuel Springer 0
Uri Gottlieb 2
Uria Moran 2
Guy Verhovsky 2
Ran Yanovich 1
0 Department of Physical Therapy, Ariel University , Ariel , Israel
1 Institute of Military Physiology, IDF Medical Corps , Tel-Hashomer , Israel
2 Israel Defense Force Medical Corps , Zerrifin , Israel
Background: Chronic ankle instability (CAI) is attributed to functional instability driven by insufficient proprioception. However, it is not clear whether the deficits are related to global impaired performance or to specific decrease in ankle motor-control. The aim of this study was to assess the correlation between lower limb postural control and upper limb position sense among people with CAI, in order to further explore the function of the central neural control in people with CAI. Methods: Fourteen participants (10 males, 4 females) with self-reported CAI and 14 age- and gender-matched, healthy controls participated in this study. Each participant completed single-limb stance postural control tests and shoulder position sense tests. The Overall Stability Index (OSI) was used as a measure of postural stability. The average of the absolute error score (AES) was calculated as a measure of shoulder position sense. Pearson correlations between the scores of the four body sites -lower limb postural stability (preferred/non-preferred), shoulder (preferred/non-preferred) were determined separately for each group. Results: In the control group, significant correlations were found between the OSI score of the right and left ankles (r = 0.887, p < 0.001), between the AES of the right and left shoulders (r = 0.656, p = 0.011), as well as between the OSI score and the AES of the non-preferred side (r = 0.649, p = 0.012). In the CAI group, significant correlation was found only between the OSI score at both ankles (r = 0.6, p = 0.002). Conclusions: Individuals with CAI demonstrated lower limb postural control and upper limb position sense similar to those shown in healthy controls. However, correlations between the lower and upper limbs were observed only in the healthy controls. Clinicians can use this information and employ activities that focus on coordinating the upper and lower extremities when designing neuromuscular control training programs for people with CAI.
Proprioception; Ankle-sprain; Chronic ankle instability
Ankle sprains occur frequently in athletes and
activeduty soldiers, as well as among the general population
[1, 2]. Although often considered minor, the long term
consequences of ankle sprain may have major impacts
on health and daily life . For example, 72 % of people
post-ankle injury reported that they were functionally
impaired by their ankle, in most cases unable to perform
sports at a desired level .
Recurrent ankle sprains occur in 70 % of individuals
that have experienced a lateral ankle sprain previously.
The cause of this high level of recurrence is currently
unknown . Individuals who report on residual
symptoms, which include repetitive episodes of ankle joint
instability and feeling of ‘giving way’, have been termed
as having chronic ankle instability (CAI) . It has been
suggested that this CAI can be attributed to functional
instability driven by insufficiencies in proprioception and
postural control , which can be defined as the inability
to maintain stability above a narrow base of support in
single-limb stance . However, two recent systematic
reviews of postural stability, including a meta-analysis,
that aimed to determine whether postural control is
adversely affected in those with CAI, indicated that such
deficits have not been detected consistently in this
population [9, 10]. Therefore, it was recommended that the
clinical diagnosis of CAI should not be based solely on static
postural control testing, but rather on more challenging
and complex evaluations of sensorimotor performance .
Previous reports that tested proprioception in
ablebodied participants, have presented conflicting results.
Some studies suggested that proprioception is site-specific,
meaning that there is likely to be a common control
program for the same joint on the two sides of the body, and
that the program uses proprioceptive information from
sources that are specific to those joints [11, 12]. Contrary
evidence, however, suggests that proprioception may be a
general body attribute. Hence, it is expected that
participants with proprioceptive deficits at one site may have
generally poor proprioception at other body sites [13, 14].
Another finding related to proprioception is side-general
asymmetry, in terms of non-dominant side proprioceptive
superiority. This phenomenon has been demonstrated by
several recent studies that evaluated lower and upper
limb joints [12, 15, 16]. Studies of people with ankle
injuries indicated bilateral associations of unilateral injury
by demonstrating sensorimotor deficits of both injured
and uninjured ankles [17, 18]. However, it is not clear
whether the deficits in the uninjured ankle are related to
global impaired performance, or to a specific decrease in
motor control in the ankle joints. To the best of our
knowledge, upper limb proprioceptive abilities and the
connection between sensorimotor performance in the
upper and lower limbs, among people with recurrent
ankle injuries have not been evaluated previously.
The aim of this study was to assess the correlation
between two aspects of sensorimotor function, lower
limb postural control and upper limb position sense in
participants with recurrent ankle sprains. This
evaluation can contribute to a better understanding of
sensorimotor function in this population, and may provide
knowledge to effectively evaluate and treat recurrent
The study included 28 participants, a group of 14
with CAI and 14 age- and gender-matched,
ablebodied controls. The enrolment criteria for the CAI
group were based on inclusion criteria for
investigating CAI as suggested by Delahunt et al. .
Participants were recruited for the CAI group if they had:
(i) a history of at least one significant ankle sprain which
occurred at least 12 months prior to enrolment in the
study and was diagnosed by a physician or a physical
therapist using clinical examination classifications described
by Malliaropoulos et al. , (ii) a history of at least two
episodes of ‘giving way’, and feelings of ankle joint
instability  in the previously injured ankle joint of
1 year post-initial sprain, (iii) the most recent injury
occurred more than 6 weeks prior to the study enrolment,
(iv) the ability to apply full weightbearing on the injured
lower extremity with no more than mild discomfort.
Exclusion criteria for this group were: evidence of a
concomitant injury (such as a bony injury or significant muscular/
tendon injury), previous ankle surgery, other pathological
conditions or surgical procedures in either upper/lower
extremity, neurological/vestibular or any other balance
disorder. The control group included healthy participants
with no current or previous conditions that could affect
proprioception, in particular: the presence of joint injuries
within the past 6 months, a chronic disease (e.g., multiple
sclerosis, stroke, Parkinson’s disease, rheumatoid arthritis,
or type 2 diabetes), or any history of visual or vestibular
disturbance affecting balance.
Both groups included only participants who
demonstrated right upper and lower limb preference. Handedness
was measured using the ten-item version of the Edinburgh
Handedness Inventory (EHI) . Laterality score for
participants was an EHI +50 to +100 (where scores of +100
represent an extreme right hander and scores of −100
represent an extreme left hander). Footedness was
measured using the Waterloo Footedness Questionnaire
(WFQ) , scores from +7 to +20 indicate right-footed
(where scores of −7 to −20 indicate left-footed, and
scores between −6 and + 6 indicate mixed-footed).
The study was approved by the Israel Defense Force
Medical Corps Ethical Review Board (approval number
IDF-1379-2014). All participants provided written
informed consent to participate in the study.
Postural assessment was carried out using the Biodex
Stability System (BSS) (Biodex Corp, NY, USA). The BSS is
comprised of an unstable support platform that allows up
to 20° of multi-axial surface deflection. The BSS can be set
at 12 levels of stability, with 12 the most stable foot
platform setting and 1 the least stable. The measures of
postural stability were obtained at stability level 3 and included
the overall stability index (OSI), which measures the
variance of foot platform displacement in degrees in all
directions: sagittal plane anterior/posterior and frontal plane
medial/lateral stability. This stability index represents the
mean angular displacement of the platform in degrees from
the zero-point position. Higher scores indicate greater
difficulty maintaining the platform in a stable position; hence,
poorer balance stability. Conversely, lower scores represent
better stability and better balance. The reliability of the
BSS has been established, with an intraclass
correlation coefficient ranging from 0.72 to 0.81 .
The postural control testing was performed with the
participants barefoot, in single-limb stance, in the
central region of the platform while keeping the
unsupported limb in a comfortable position so as not to
contact the tested limb or the test platform (Fig. 1).
Participants were instructed to look straight ahead
and to keep the platform as motionless as possible
for 20 s. Each participant was given a familiarisation
session. Two measurements were taken for each limb
in random order, with a two minute rest interval
between trials. The average of the two evaluations was
used for data analysis. This method has previously
been used to assess postural control in participants
post ankle sprains [23, 24].
The shoulder was chosen for measuring of upper
extremity joint position sense, since, similar to the ankle,
motor control plays a significant role in ensuring the
joint stability . The Biodex Multi-Joint System
(Biodex Corp, NY, USA) was used for the position sense
test of the shoulder. The system includes an
electrogoniometer, which is sensitive to 1° increments .
Active angle repositioning was measured with the
participants in a seated position, with their back vertical, the
shoulder positioned at 90° of abduction and 90° of
external rotation in the plane of the scapula (30° in front
of the frontal plane), and the forearm perpendicular to
the floor (90° of flexion at the elbow) (Fig. 2). This
position was selected to simulate the abducted, externally
rotated position of the shoulder required in many
activities. Participants were blindfolded to eliminate visual
cues related to joint position.
After setting the starting position, the participant’s
shoulder was passively moved to one of the test angles
(45° or 60° of shoulder external rotation) by the
examiner. Participants were asked to concentrate on the
sensation of the presented angle for three seconds. Then,
the participant’s shoulder was passively returned to the
starting position by the examiner. Following a three
second rest period, the participant was asked to actively
reproduce the presented joint angle. Once the
participant felt that the shoulder was in the position of the
presented angle, he/she pressed the hold switch, preventing
the dynamometer from further movement. Each subject
underwent a short mock test (45° of shoulder external
rotation) with each limb to ensure comfort and
understanding of the test protocol. Then, the procedure was
repeated twice more for the 45° target angle (three times
in total) and three times for the 60° target angle.
Measurements were taken with both limbs in a randomised
order with a two minute rest between trials. The average
of the absolute error score (AES) was calculated (i.e., the
difference between the reproduced angle and the target
angle) and used for data analysis. Previous research has
found this technique to be an accurate and reliable method
of measuring shoulder joint position sense [25, 27].
Fig. 1 Postural control testing. Note. Participants stood in
singlelimb stance in the central region of the Biodex Stability System
platform. Participants were instructed to look straight ahead and to
keep the platform as motionless as possible for 20 sec
Fig. 2 Shoulder position sense testing. Note. Participants were
secured into the seat of the Biodex Multi-Joint System and then the
shoulder was positioned at 90° of abduction and 90° of external
rotation in the plane of the scapula, with the forearm perpendicular
to the floor. Participants were asked to actively reproduce the
passively set index angle
Time (weeks) since last sprain
CAI chronic ankle instability, RT right, LT left, BIL bilateral
The Anderson-Darling test was used to assess data
normality; however due to the lack of normal distribution,
nonparametric analysis was used. The Mann–Whitney
test was applied to compare baseline characteristics as
well as the performance (i.e., OSI and AES) between the
CAI and control groups. The performance in the
nonpreferred/left (upper and lower limb measures) versus
the preferred/right for each group was compared using
Wilcoxon matched pairs test. Likewise, the Wilcoxon
matched pairs test was used to test for differences
between groups. This test was also employed to compare
the OSI in the limb with recurrent sprains versus the
unaffected limb, in the CAI group. Pearson correlations
between the scores of the four body sites, namely lower
limb (preferred/right and non-preferred/left) and
shoulder (preferred/right and non-preferred/left), were
determined for each group separately. Finally, the Z test was
used to determine whether any difference existed
between the correlations in the CAI group versus the
control group. SAS V9.3 (SAS Institute, Cary, NC, USA)
was used for statistical analyses. Significance was set at
p < 0.05.
Data on participant characteristics are summarised in
Table 1. There were no differences in baseline
characteristics (age, BMI, EHI handedness score, and WFQ
Footedness score) between the CAI and control groups.
Effect of group (CAI vs. Control), side (non-preferred/left vs.
preferred/right), and affected limb
Table 2 presents the median and interquartile range of
the measured outcomes of each group, as well as
comparisons between groups. Comparisons of the
performance in the non-preferred/left side vs. the preferred/right
side for each group, and for the entire sample, are
also provided. Comparisons (OSI right/left and AES
Table 1 Participant characteristics (median and interquartile range)
right/left) demonstrated no difference in all outcomes
between the CAI and the control group.
Comparisons of the performance in non-preferred/
left vs. the preferred/right side yielded no effect for
side (i.e., right/left, see Table 2). Though no
significant effect was found for preferred/non-preferred
side, a strong trend was demonstrated for superiority
of the right preferred side when analysing the results
of the OSI in the entire sample (p = 0.051).
The comparison of the OSI in the limb with recurrent
sprains versus the unaffected limb included the 12
participants in the CAI group who had unilateral recurrent
sprains (see Table 1). No difference was found between
the OSI score in the two limbs (p = 0.490).
Correlations between body sites
Pearson correlations between the scores of the four body
sites yielded differences between the CAI and control
groups (Table 3). In the control group, significant
correlations were found between the OSI score for the right
and left foot (r = 0.887, p < 0.001), between the AES for
the right and left shoulder (r = 0.656, P = 0.011), and
between the OSI score and the AES for the non-preferred/
left side (r = 0.649, P = 0.012). In the CAI group, a
significant correlation was found only between the OSI
score for the right and left foot (r = 0.600, p = 0.002).
The Z tests, indicated that there was a significant
difference in correlations between the two groups only in the
correlation of the OSI score and the AES for the
nonpreferred/left side (p = 0.037).
This study investigated the sensorimotor function of
different body sites in participants with recurrent ankle
injuries. As noted in recent systematic reviews [9, 10],
postural stability measures in single-leg stance did not
discriminate between participants with CAI and those
without, as well as between the limb with recurrent
sprains versus the unaffected limb in the CAI group. It
should be noted, however, that while the measure of
static postural stability may not be sensitive enough to
detect deficits associated with CAI, more dynamic
assessments, such as the single-leg-hop stabilisation
maneuver, may have the ability to defer between individuals
with CAI and individuals with stable ankles [28, 29]. In
addition, reports of postural assessment through the
Balance Error Scoring System have also shown promise
in detecting differences between those with and without
Similar to lower limb postural stability results, there
was no difference in the shoulder position sense
between the CAI and control groups. This is consistent
with the findings of Hung et al. , who found that
people with unstable shoulders can perceive active
Table 2 Group outcome measures (median and interquartile range) and comparisons
Comparison - CAI vs.
CAI chronic ankle instability, OSI overall stability index, AES absolute error score, RT right, LT left
Comparison - preferred/right vs. non-preferred/left P-value
CAI group (n = 14) Control group (n = 14) Entire sample (n = 28)
0.134 0.237 0.051
shoulder angles as accurately as those with healthy
While the sensorimotor function of the different body
sites was similar in both groups, examination of the
correlations between the body sites differentiates the
groups. In the able-bodied group, Pearson correlations
showed significant positive correlations between the
same joint on the right and left sides, as well as
significant positive correlations between the upper and lower
limb in the non-preferred/left side. This may suggests a
site-specific and a non-preferred side attribute in the
way the brain integrates proprioceptive information.
However, in the CAI group there was no correlation
between the upper and lower limb and significant positive
correlations were found only between the lower limb on
the right and left sides.
Table 3 Pearson correlations between the mean scores of the
lower limb (preferred/right and non-preferred/left) and shoulder
(preferred/right and non-preferred/left)
p = 0.023
p = 0.893
p = 0.264
p = 0.365
p = 0.108
p = 0.242
p = 0.698
p = 0.083
p = 0.135
p = 0.012
p = 0.011
CAI chronic ankle instability, RT right, LT left, OSI overall stability index,
AES absolute error score, RT right, LT left
It has been suggested that joint injury may be more
likely to occur when there is a “pre-existing, global
deficit” in proprioception . It is not clear whether
individuals with CAI have a “pre-existing, global deficit”.
However, the lack of correlation demonstrated in the
CAI group may suggest difference in the sensorimotor
integration and processing post-injury, when compared
to healthy participants. Dynamic movements involving
multiple body segments, such as locomotion, require
controlling and coordinating the arms and legs to
accomplish a rhythmic, smooth, movement pattern .
Indeed, it has been shown that people with recurrent
ankle sprains may have a typical altered gait pattern that
might be related to altered control of the central nervous
system [33, 34]. Furthermore, in a study that compared
the effect of dual tasking on postural performance in
participants with CAI and a matched control group,
concurrent performance of a cognitive task decreased
postural stability only in the participants with CAI .
This may also suggest a deficit in central neural control
for maintenance of balance in that group. To our
knowledge, the present study is the first to describe the lack
of correlation in sensorimotor function in a sample of
participants with recurrent ankle sprain.
The greatest challenge presented by CAI may not be
in treatment, but in prevention . A recently
published position statement by The National Athletic
Trainers Association, intended to provide
recommendations for conservative management and prevention of
ankle sprains, indicated that clinicians should implement
a multi-intervention injury-prevention program that
focuses on balance and neuromuscular control to reduce
the risk of ankle injury . Our results suggest that this
multivariate approach should include sensorimotor
exercises and tasks that coordinate the upper and lower
extremities. For example, throwing a ball toward a specific
target, while standing in a single limb stance on a
wobble board or soft surface. It is also recommended that
accurate assessment and documentation of progress of
such activities should be a standard part of
It has been suggested that there is non-preferred limb
superiority in the utilisation of proprioceptive feedback.
The advantage of the non-preferred limb is attributed to
the functional differences between the roles of limbs
especially in bilateral tasks. The non-preferred limb usually
stabilises a specific position to enable the preferred limb
to manipulate and perform a task . For example,
while hammering a nail or kicking a ball. Thus, joints in
non-preferred limbs are more likely to receive more
“positioning” practice, resulting in more accurate
discrimination of movement. The results in the control
group, which demonstrated correlation between the
upper and lower limb only in the non-preferred (left)
side may support this ‘superiority’ hypothesis.
Nevertheless, as reported by previous studies [25, 38], the study
results did not demonstrate differences in the tested
performances between the preferred and non-preferred
shoulder and ankle. A possible explanation may be
related to the joints tested and the evaluation method in
the current study. Proprioceptive asymmetry was mainly
evident at distal joints and under non-weightbearing
conditions [39–41]. However, the present study included
only one distal joint (i.e., the ankle), which was evaluated
in a weightbearing condition. Furthermore, the
evaluation was of postural control that is affected by
proprioception as well as by the motor control system.
Therefore, it is not surprising that asymmetry was not
reported in the present study. Future studies with
multiple joints should be conducted to evaluate whether
proprioceptive asymmetry exits.
The present study has several limitations. Firstly,
different aspects of sensorimotor function were evaluated
in the upper (i.e., position sense) and lower limb (i.e.,
postural control). When testing sensorimotor function
and acuity, it is important that the tests maximise
external validity (i.e., the similarity between the laboratory
and real life function) . The shoulder test was
selected to simulate the abducted, externally rotated
position of the shoulder required in many sporting activities
and the ankle test was chosen as it has the advantage of
testing in the weightbearing position. The similarity of
these tests to normal function enhances the external
validity of the current study. Nevertheless, future
investigations in people with CAI should examine inter-limb
correlations using the same aspects of sensorimotor
function. Secondly, the study cohort consisted of a
relatively small sample, with a narrow age range, and it
included only participants who demonstrated right upper
and lower limb preference. Thirdly, while the enrolment
criteria for the CAI group were based on self-reporting
of ‘giving way’ and feelings of ankle joint instability, it
did not include the use of an ankle instability
questionnaire, such as the identification of functional ankle
instability (IdFAI) ; By not using the ankle instability
questionnaire eliminated our ability to quantify this
aspect of perception. Future studies with larger and varied
samples that also confirm self-reported ankle instability
with a validated ankle instability-specific questionnaire,
Participants with CAI demonstrated lower limb postural
control and upper limb position sense similar to those of
healthy controls. However, correlation between lower
and upper limbs was observed only in the healthy
controls. These results may be explained by a deficit in the
central neural control of sensorimotor integration and
processing in people with CAI. Clinicians can use this
information when designing neuromuscular control
training programs for people with CAI and potentially reduce
the risk of re-injury.
CAI: Chronic ankle instability; OSI: Overall stability index; AES: Absolute error
score; EHI: Edinburgh Handedness Inventory; WFQ: Waterloo Footedness
Questionnaire; BSS: Biodex Stability System; SD: Standard deviations;
BMI: Body mass index.
SS conceived the study and participated in the design, data collection,
statistical analysis and manuscript preparation. UG participated in the design
of the study, data collection, and manuscript preparation. UM participated in
the design of the study, data collection, and manuscript preparation. GV
participated in the design and coordination of the study and helped to draft
the manuscript. RY participated in coordination of this study and with all
other authors involved in preparation for submission for publication. All
authors read and approved the final manuscript.
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