Vol 43 # 2 June 2011 - Kma.org.kw

June 2011
KUWAIT MEDICAL JOURNAL 103
unilateral stance test showed a significant increase of
mean (± SD) COG sway velocity on left or right leg
standing with eyes open and eye closed in athletes with
chronic ankle sprain as compared to control group (p
< 0.05). Moreover, there was a significant increase of
mean (± SD) percentage difference score with eyes
open and eyes closed in athletes with chronic ankle
sprain as compared to control group (p < 0.001).
According to the National Collegiate Athletic
Association [15] , ankle sprains are the most common
injuries in men and women who participate in soccer,
basketball, and volleyball. Most ankle sprains are
inversion injuries that damage the lateral ligaments
of the ankle [16] . Upto 73% of individuals who sprain
their ankles have residual symptoms including pain,
repeated sprains, and episodes of ‘‘giving way’’ [17] .
A previous study found that after an ankle sprain,
up to 40% of patients continued to report residual
disability [18] which might be persistent for seven years
after inversion trauma [19] .
Our results are in agreement with various other
studies which revealed increased postural instability
after ankle injury. In addition, other authors [20-22] have
found an increase in various objective measures of
postural control including measurements of centerof-pressure
excursion length (LEN), root mean square
velocity (VEL), and excursion range (RANGE) in
injured limbs versus contralateral uninjured limbs
after ankle sprain [20] .
Golomer et al [21] demonstrated significant
impairments of various objective measures of postural
control including measurements of LEN and VEL, in
injured limbs compared with uninjured limbs among
five subjects between 4 - 15 days after ankle sprain.
Leanderson et al [22] showed significant increases in
COP excursion variables in injured limbs compared
with uninjured limbs among six ballet dancers within
two weeks of experiencing ankle sprain. Each of these
six injured dancers’ postural control scores returned to
preinjury levels with structured rehabilitation.
Hertel et al [14] demonstrated a significant
impairment in postural control after ankle sprain.
Measurements of impaired postural control including
LEN, VEL, and RANGE were elevated in injured limbs
versus uninjured limbs in the frontal plane and in the
sagital plane. Orteza et al [23] demonstrated impaired
balance on a testing device similar to that of Golomer
et al [21] among subjects of ankle sprain compared with
a group of healthy controls. Guskiewicz and Perrin [24]
demonstrated impaired postural control of ankle
sprain among injured limbs compared with the limbs
of healthy controls. Poor postural stability has also been
reported to predispose physically active individuals to
ankle sprains [25] .
However, our results are in contrast to some
previous studies such as Bernier et al [26] which did not
find significant difference in postural sway between
patients with ankle instability and control group.
Tropp et al [27] found that mechanically unstable
ankles did not show a decreased ability to maintain
postural stability when measured with stabilometry
under static conditions. One possible explanation of
differences with other authors may be the method of
subject recruitment and techniques.
The potential explanation for the deficits in
postural control after ankle sprain in our results may
be due to several factors. Freeman et al [28] originally
hypothesized that balance impairments after ankle
sprain were the result of impaired proprioception
due to damage to joint mechanoreceptors and
afferent nerve fibers, which occurs in conjunction
with ligamentous damage during hyperinversion.
Impaired proprioception may cause diminished
or delayed muscle response that provide dynamic
stability to the ankle joint resulting in inadequate
corrections to postural perturbations [29-30] .
Another explanation of impaired postural control
might be due to altered proximal muscle activity in
response to ankle injury. Subjects with ankle injuries
have been shown to shift from the typical ankle
strategy of balance maintenance during single leg
stance to the less efficient hip strategy of balance [31-32] .
Another potential cause of impaired postural control
after lateral ankle sprain is that lateral ligamentous
injury may result in mechanical instability of the
subtalar and talocrural joints and allow greater ranges
of pronation and supination to occur during singleleg
stance, thus resulting in greater magnitude and
velocity of center-of-pressure (COP) excursions [21-24] .
CONCLUSION
This study represents the first attempt to use the
dynamic posturography equipment as a diagnostic
tool in assessment of impaired postural control in
athletes with ankle sprain in Kuwait. Our study
identifies quantifiably the impairment in postural
control that might help to predict which athletes are
predisposed to develop long-standing functional
instability after ankle sprain injury.
The chronic ankle sprain has higher than normal
COG sway velocity and impaired postural control.
The ligamentous damage, ankle muscle strength
deficits and proprioception deficits at the ankle joint
may explain poor balance in ankle sprain. Future
researches should include the effect of rehabilitation
programs on single-leg stance in chronic ankle
sprain.
ACKNOWLEDGMENTS
We acknowledge the assistance of our colleagues
in Physical Medicine and Rehabilitation Hospital,
Kuwait.