Authors:
Mehrsheed Sinaki, MD, MS
Susan G. Lynn, MA
Balance
Affiliations:
From the Department of Physical
Medicine and Rehabilitation (MS) and
the Division of Audiology (SGL),
Mayo Clinic, Rochester, Minnesota.
Research Article
Disclosures:
Presented, in part, at the Annual
Meeting of the American Society for
Bone and Mineral Research, St.
Louis, MO, October 3, 1999.
Correspondence:
All correspondence and requests for
reprints should be addressed to
Mehrsheed Sinaki, MD, MS, Mayo
Clinic, 200 First Street SW,
Rochester, MN 55905.
0894-9115/02/8104-0241/0
American Journal of Physical
Medicine & Rehabilitation
Copyright © 2002 by Lippincott
Williams & Wilkins
Reducing the Risk of Falls Through
Proprioceptive Dynamic Posture
Training in Osteoporotic Women
with Kyphotic Posturing
A Randomized Pilot Study
ABSTRACT
Sinaki M, Lynn SG: Reducing the risk of falls through proprioceptive
dynamic posture training in osteoporotic women with kyphotic posturing:
A randomized pilot study. Am J Phys Med Rehabil 2002;81:241–246.
Objective: To assess the effect of a proprioceptive dynamic posture
training program on balance in osteoporotic women with kyphotic posture.
Design: Subjects were randomly assigned to either a proprioceptive
dynamic posture training program or exercise only group. Anthropometric measurements, muscle strength, level of physical activity, computerized dynamic posturography, and spine radiography were performed at baseline and 1 mo.
Results: At the 1-mo follow-up, three groups were formed on the
basis of the baseline computerized dynamic posturography results. In
general, groups 1 and 2 had no significant change at 1 mo, whereas
group 3 improved balance significantly at 1 mo.
Conclusion: The subjects who had abnormal balance and used the
proprioceptive dynamic posture training program had the most significant
improvement in balance. Improved balance could reduce the risk of falls.
Key Words: Balance, Exercise, Falls, Osteoporosis
April 2002
Reducing the Risk of Falls in Osteoporosis
241
A
lthough pharmacotherapy is essential in the treatment of osteoporosis, its efficacy in prevention of osteoporotic falls and fractures should not
be overrated. The skeletal and psychological benefits provided by musculoskeletal rehabilitation are also
important. Physical medicine and rehabilitation programs are justifiably
fundamental to the management of
osteopenia and osteoporosis. Ongoing research is attempting to develop
treatment for osteoporosis, and investigators are also focusing on preventive measures, including hormone replacement therapy, exercise,
and dietary interventions. An area
that has received less attention in the
field of osteoporosis research is the
prevention of falls. Several studies
have shown the life-threatening complications associated with falls.1,2 Approximately 30% of all women and
20% of all men older than 50 yr will
fall each year.3 Although multiple
factors often contribute to a fall,1 impaired balance is an important element.2,4 Even in relatively healthy,
independent-living seniors, there is a
high correlation between poor balance control and the incidence of
falls.3,5 Nguyen et al.6 reported that
body sway was an independent predictor of fracture prevalence in 1479
subjects and concluded that determination of balance was important to
the prediction of falls and fracture.
Recent studies have focused on balance changes that are likely to occur
in the elderly.7,8
Given that impaired balance is
associated with an increased propensity to fall,4,9 improvements in balance may reduce that risk. The flexed
posturing that often develops in elderly persons may place their center
of gravity closer to their limit of stability.5 This feature is also expected in
subjects with kyphosis caused by osteoporosis. In a previous study,10 the
authors found that patients with osteoporosis who had kyphosis had
greater reliance on hip strategies
242
Sinaki and Lynn
during computerized dynamic posturography (CDP) than those who did
not have kyphosis. They also had
more postural sway. Randomized order of trials with and without proprioceptive dynamic posture (PDP)
showed no significant changes in
postural sway or in balance strategies
when subjects used PDP. This study
was designed to determine whether
such changes could be measured after long-term use of the PDP. The
objective of this study was to determine whether an uncomplicated program using proprioception along
with exercises such as a PDP training
program could improve balance11 in
osteoporotic women with kyphotic
posture.
METHODS
Subjects
After we obtained Institutional
Review Board approval, seven women
between the ages of 70 and 83 yr with
osteoporosis who had been evaluated
in our osteoporosis clinic were asked
to participate in the study. Subjects
who met the inclusion criteria were
enrolled in the study. The study included only local women who were
older than 65 yr and had a diagnosis
of osteoporosis confirmed through
radiographic changes of the spine
(such as ballooning of disks, anterior
wedging, nontraumatic compression
fractures of vertebral bodies, loss of
horizontal trabeculae, and end-plate
opaqueness) and measurement of the
bone mineral density of the spine
with dual photon absorptiometry.12
Subjects were included if their
thoracic kyphosis, measured on
standing lateral radiography of the
spine, showed a Cobb angle of 50 – 65
degrees.13 Subjects had to sign an
informed consent statement and be
willing to return for follow-up. Subjects were not included in the study if
they had a history of any progressive
neurogenic or myopathic disorder
that was known to impair motor
function or if they were receiving
drugs known or presumed to affect
the central nervous system or equilibrium, such as sedatives or anxiolytics. Other drugs that prohibited a
subject’s participation in this study
included diazepam (Valium), lorazepam (Ativan), alprazolam (Xanax),
flurazepam (Dalmane), triazolam
(Halcion), phenobarbital, secobarbital (Seconal), butabarbital (Butisol),
chlorpromazine (Thorazine), promazine (Sparine), thioridazine (Mellaril), trifluoperazine (Stelazine), and
prochlorperazine (Compazine). Subjects were also excluded if they used
drugs known to affect muscle
strength (e.g., corticosteroids) or if
they abused alcohol.
At baseline, all subjects had assessment of their level of pain (scale
of 0 –10, with 0 being no pain), physical activity level, CDP, and muscle
strength. Subjects kept a daily diary
of their pain level during the 4-wk
study and were monitored at 2 wk to
assess their level of physical activity
to make sure they were following the
exercise program but not adding any
additional strenuous activities. At the
end of 4 wk, each subject’s pain level,
physical activity level, CDP, and muscle strength measurements were
again evaluated.
The subjects were randomly assigned to one of two groups. One
group received back extensor
strengthening exercises only. The
other group received the same exercise program plus PDP training with
the use of a 2-pound weighted kyphoorthosis to be worn daily for 2 hr only
during ambulatory activities (Posture
Training Support) (Fig. 1).14 Participation in this study was strictly voluntary, and no remuneration was offered or provided to participants.
After preliminary assessment of the
data, the group that had PDP training
was subdivided into two groups on
the basis of their baseline scores of
CDP:15 those who had a normal composite score on baseline CDP and
those who had an abnormal compos-
Am. J. Phys. Med. Rehabil.
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Figure 1: Posture Training Support
(PTS). All subjects assigned to use
the PTS were asked to follow the exercise program that is integral to use
of the PTS. The PTS is a weighted
kypho-orthosis that is applied to the
back at the level of the scapulae. It
encourages the use of back extensor
muscles and helps to shift the center
of gravity to aid in repositioning the
spine to maintain upright posture as
normal as possible. (Modified from
Posture Training Support,14 with the
permission of Mayo Foundation.)
ite score on baseline CDP. Therefore,
the three study groups were group 1
(exercise therapy only and abnormal
baseline CDP), group 2 (exercise plus
PDP training, normal baseline CDP),
and group 3 (exercise plus PDP training, abnormal baseline CDP).
Assessments
CDP. CDP assesses both sensory organization and motor control components of balance. CDP is a safe, noninvasive procedure that takes approximately 20 min to perform.15 In our
study, the sensory organization part of
CDP was used to assess balance. The
motor control section of CDP was not
used because it was not found to be
useful in a previous study.10
In this study, the clinician performing CDP was blind to the study
group assignment of the subjects. All
subjects underwent the CDP test
twice in succession; the first CDP test
was performed without use of the
Posture Training Support, and the
second test was done with the PosApril 2002
ture Training Support. A subject’s
positioning on the forceplate remained consistent throughout all
testing as judged by the placement of
the feet in relation to a grid affixed to
the footplate. Indices of postural stability assessed were the composite
score and the average scores of all
trials of subtests 5 and 6. Repeat testing was done 1 mo later and followed
the same protocol.
The sensory organization portion
of the CDP test attempts to isolate
each of the three sensory systems involved in maintaining balance to determine a patient’s ability to use the
systems effectively. The patient
stands with a safety harness in place
on a platform facing a colored visual
surround and is asked to maintain
balance. Each trial is 20 sec long, and
up to three trials can be performed
for each subtest. The feet are placed
in a position that provides a broad
base of support. Pressure transducers
under the footplate, with calculations
for height and weight of the subject,
allow measurement of the degree of
postural sway relative to the 12.5 degree cone of stability. A score of 0
represents instability to the point of
falling or having to step. A score of
100 represents no sway. A single
transducer measures shear force or
horizontal displacement on the platform. Horizontal forces on the platform increase relative to vertical
force when the subject flexes at the
hips rather than at the ankles to
maintain balance (Fig. 2). Sensory
subtests 5 and 6, the most difficult of
the subtests, involve elimination of
inaccuracy of visual and somatosensory cues. Reliability of the sensory
organization tests has been assessed
through evaluation of the same 45
subjects on different days; this
showed a less than 10% improvement
on sensory conditions 5 and 6.15
Standardized Radiographic Evaluation. Each subject had lateral thoracic and lumbar radiographs obtained at baseline to determine
Figure 2: Six subtests of the sensory
organization test of computerized dynamic posturography. Subtests become progressively more difficult as
sensory information is altered. (From
Lynn et al.10, with the permission of
the American Congress of Rehabilitation Medicine and the American
Academy of Physical Medicine and
Rehabilitation.)
Cobb angle and kyphosis and at 1
mo to determine any significant radiographic changes (i.e., fracture or
subluxation).16
Strength Measurements. Back extensor strength was measured at baseline and 1 mo (without knowledge
of the subject’s other laboratory results) with a strain-gauge isometric
dynamometer (BID-2000, Mayo
Clinic, Rochester, MN), according
to a standardized technique. This
device provides a safe, reliable (coefficient of variation, 2.33%), and
valid (P ⫽ 0.001) method of
evaluation.17
Dominant and nondominant
maximal grip strength was measured
to evaluate changes in general muscle strength. A JAMAR dynamometer
(Jamar, Jackson, MI) was used to determine maximal grip strength at
baseline and 1 mo. This device has
been used in several other studies to
measure grip strength.18,19
Knee extensor strength assessment consisted of measuring 10 maximal repetitions (i.e., the maximal
weight that can be moved through a
full range of motion for 10 repetitions) with sandbag weights ranging
from 1 to 25 pounds. Subjects were
seated on a table with their body positioned in 90 degrees of hip flexion
Reducing the Risk of Falls in Osteoporosis
243
TABLE 1
Baseline and 1-mo characteristics
Group
Subject
Age, yr
Balance (CDP),
normal ⱖ68
Height, cm
Weight, kg
0
0
1 mo
0
1 mo
153
145
38
37.8
38
37.3
60
49
155
153.8
59
64.5
61
64.5
145.9
153.5
154
54
61.0
63.6
54.2
61.0
63.6
Exercise only, abnormal baseline CDP
1
70
153
2
82
147
Exercise, PDP, normal baseline CDP
3
71
153.5
4
70
152.8
Exercise, PDP, abnormal baseline CDP
5
81
145.8
6
74
153.5
7
83
154
1 mo
PAS, 0-18
Pain, 0-10
Change
0
1 mo
0
1 mo
58
52
⫺2.0
⫹3
6
3
7
6
10
5
7
4
77
88
82
86
⫹5
⫺2
2
6
6
8
10
10
4
2
33
58
56
70
71
74
⫹37
⫹13
⫹18
2
4
4
7
6
8
9
6
8
4
2
5
CDP, computerized dynamic posturography; PAS, physical activity scale; PDP, proprioceptive dynamic posture training
(includes use of a Posture Training Support); 0, baseline.
and 90 degrees of knee flexion with
the palmar aspect of the hand resting
on the subject’s thigh. Weighted
sandbags were placed on the dorsum
of the talocalcaneal joint; the weight
selected allowed a maximum of 10
repetitions with periods of 5 sec holding and 5 sec resting. Subjects were
instructed to extend the leg, without
a jerking motion or extending of the
spine, within an arc of motion until
the heel was parallel to the floor. A
5-sec rest period was allowed between
contractions until all 10 repetitions
were completed. The maximal weight
lifted was documented in pounds and
converted to newtons, and the process was repeated on the contralateral leg.
Physical Activity Level. Lifetime history of physical activity was assessed
by a face-to-face interview, without
knowledge of the subject’s muscle
strength or bone mineral density, and
by a questionnaire based on our previously published standardized scale
(Physical Activity Score) that reflects
the total level of daily physical activities, including homemaking (0 – 6),
job (0 – 6), and sports (0 – 6).20 This
questionnaire was designed to assess
the level of daily physical activity by
converting the amount of weight lifting and walking involved in house-
244
Sinaki and Lynn
work, job, and sports into METs (1
MET is the metabolic oxygen requirement under basal conditions, which
is equal to the basal metabolic
rate).20,21 For instance, the category
of homemaking considers shopping
and cooking as activities after a daily
job away from home, whereas if a
person’s job is homemaking, the
scale considers that more housework,
laundry, and perhaps child care are
done during the day. Tables from the
American Heart Association were
used to assign METs to a subject’s
daily activities.21 For example, activities that require 1.5–2 METs are considered to be very light and were
scored as 0, whereas activities that
require 8 –10 METs or more were
considered very heavy and were
scored as 6. The reproducibility of
this scale was evaluated by six physicians who independently scored the
same 10 volunteer women on each
of three activities.20 For those 10
subjects, the median interexaminer
coefficient of variation was 19%,
which is acceptable for clinical follow-up.20 All evaluations for this
study were performed by the same
examiner. The reproducibility of
technique for the same examiner
has demonstrated a coefficient of
variation of 2.3%.17
Level of Pain. Each subject’s level of
back pain was measured with a pain
scale of 0 –10. During a face-to-face
interview at baseline, each subject
was asked to state her perceived level
of back pain on a scale of 0 –10 (0, no
pain; 10, high pain). Each subject
kept a daily diary of her perceived
level of back pain during the 4-wk
study period. Level of back pain was
again assessed at the end of the study
by face-to-face interview.
RESULTS
Characteristics of the subjects at
baseline and 1 mo are depicted in
Tables 1 and 2. For the age group of
the subjects included in this study,
normal scores are above 68 on CDP.
The results of the CDP evaluation are
summarized in Figure 3. Small gains
in the CDP composite score were evidenced in group 1 (exercise only) at
the 1-mo test. The two patients in
group 1 had abnormal composite
scores on the baseline CDP test. The
change in the composite score from
baseline to 1-mo follow-up was insignificant. One patient had worsening
in the CDP score from baseline level.
The two patients in group 2 (PDP
⫹ exercise) had normal composite
scores on the baseline CDP test.
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TABLE 2
Baseline and 1-mo strength measurementsa
BES,
newtons
Group
Subject Age, yr
0
4 wk
Hip extension
(R/L), newtons
0
4 wk
Exercise only, abnormal baseline CDP
1
70 111.2 97.9 13.3/8.9 13.3/8.9
2
82
62.72 57.8
0/0
0/0
Exercise, PDP, normal baseline CDP
3
71
62.72 62.72
0/0
0/0
4
70 186.8 235.7 31.1/31.1 44.5/44.5
Exercise, PDP, abnormal baseline CDP
5
81
93.4 155.7
0/0
0/0
6
74
97.9 97.9
0/0
0/0
7
83 129
177.9
0/0
17.8/22.2
Hip flexion
(R/L), newtons
Grip
(Dominant/Nondominant),
KES (R/L), newtons
newtons
0
4 wk
0
4 wk
0
4 wk
22.5/22.5
44.5/44.5
22.5/22.5
66.7/66.7
44.5/44.5 44.5/44.5
80.8/66.7 44.5/44.5
227/178
222.4/178
244.6/204.6
231.3/182.4
22.2/31.1
66.7/66.7
48.9/44.5
89/89
22.2/31.1
40/35.6
53.4/53.4 80.1/80.1
120.1/89
182.4/200.2
133.4/93.4
182.4/204.6
44.5/44.5
111.2/111.2
35.6/35.6
44.5/44.5
111.2/111.2
66.7/66.7
44.5/31.1 44.5/31.1
66.7/66.7 66.7/66.7
44.5/53.4 53.4/57.8
146.8/155.7
222.4/177.9
191.3/177.9
133.4/160.1
244.6/133.4
177.9/155.7
BES, back extensor strength; CDP, computerized dynamic posturography; KES, knee extensor strength; PDP, proprioceptive dynamic posture training (includes use of a Posture Training Support); R/L, right/left; 0, baseline; 1 newton ⫽ 0.2248 lb.
a
0 strength indicates subject was able to lift only the extremity tested with no additional weight.
These patients did not have improvement at the 1-mo follow-up test. The
change in the composite score from
baseline was 1.5. The three patients
in group 3 (PDP ⫹ exercise) had abnormal composite scores on the baseline CDP test. However, significant
improvements were achieved at the
1-mo follow-up test when the CDP
composite sensory score became normal in all cases. The average change
in the composite score from baseline
Figure 3: Changes in balance, tested
with computerized dynamic posturography, from baseline to 1 mo in seven
subjects (A–G). Group 1, exercise
therapy only; group 2, exercise plus
proprioceptive dynamic posture training, normal baseline computerized
dynamic posturography; group 3,
exercise plus proprioceptive dynamic posture training, abnormal
baseline computerized dynamic
posturography.
April 2002
to 1 mo was 22.7. Comparison of the
three groups showed a significant
change in the CDP composite score
in group 3 only. Comparing this
change between groups, there was a
significant difference between groups
3 and 1 (22.7 vs. 0.5) and groups 3
and 2 (22.7 vs. 1.5). No changes were
found in balance strategy score in any
of the groups.
The physical activity score was
measured at baseline and 1 mo to
monitor the subjects’ day-to-day activities during the study period.
With the study exercise program
taken into account, all subjects increased their level of physical activity by 1 point from baseline. In addition, subjects in groups 2 and 3
increased their level of physical activity by an additional 1 point
through the use of the PDP program. Of interest, five of the seven
subjects had increased their day-today level of physical activity. Also of
interest, all subjects had decreased
back pain on follow-up. Body
weight stayed about the same in all
subjects. Tables 1 and 2 provide all
the variables that were checked at
baseline and 1-mo follow-up
evaluations.
DISCUSSION
This study was designed to evaluate the effect of a user-friendly method
to improve balance in subjects with
osteoporosis and kyphotic posture.
Several studies have evaluated strategies for prevention and treatment of
osteoporosis through increasing peak
bone mass and muscle strength. Increasing age, changes in proprioception, and reduction of muscle strength
contribute to the risk of falls. The risk
of falls decreases after participation in
lower extremity strengthening exercises in older individuals.22 One study
showed significant improvement in
quadriceps strength but did not show
any improvement in balance.23
In this study, a proprioceptive
technique applying a weighted kypho-orthosis was used to determine
whether balance could be improved
without a specific effort to increase
muscle strength. Muscle strength increases after 6 wk of participation in a
strengthening exercise program.24
The duration of the current study was
intentionally 1 mo—not long enough
to increase muscle strength substantially but long enough to improve
muscle recruitment, if any. We
planned our study on the basis of
Reducing the Risk of Falls in Osteoporosis
245
balance and kyphotic posture. After
baseline CDP was performed, however, we noted that even the subjects
with kyphosis could have good balance without strong back muscles in
comparison with the rest of the subjects. We concluded that proprioception had to play a role because the
weighted kypho-orthosis (Posture
Training Support) was placed at the
T10 level. The weighted kypho-orthosis placed at that level may act
through local effect on proprioception of related intervertebral joints
(T8, T9, and T10, the commonly involved vertebral bodies) and maintain
the gravity line to help balance sensory organization. Therefore, improvement of balance and rehabilitation of proprioception for postural
changes may function independent of
an increase in muscle strength. The
follow-up for this study was not long
enough to show postural changes,
but follow-up radiographs were obtained to rule out significant radiographic changes such as fracture or
subluxation. However, after completion of the study, one control subject
(subject 1, group 1) returned to us for
physical therapeutic intervention. After 3 mo, she had a decrease in kyphosis (confirmed by radiographic
examination) and improved balance.
It was of interest that all subjects
had a reduced level of pain after participation in the simple back extension
exercise program, regardless of group
randomization, and that five of the
seven subjects had increased their dayto-day level of physical activity. Perhaps these two factors are related in
that with less pain subjects were inclined to be more active (Table 1).
CONCLUSION
The results of this randomized,
controlled pilot study suggest that persons with osteoporosis who have abnormal balance and kyphotic posture
could benefit more from proprioceptive dynamic rehabilitation with a
246
Sinaki and Lynn
weighted kypho-orthosis and back exercise than from back exercise alone. A
considerable improvement in balance
was noted in subjects who did exercises
with PDP training. Improved balance
reduces the risk of falls. Although the
number of subjects in this study was
small, the results are interesting, and
further investigation on a larger scale
would be helpful.
ACKNOWLEDGMENTS
We thank the Donaldson Charitable Trust and Marjorie Atwood for support of our research related to osteoporosis and musculoskeletal health. We
thank Sandra Fitzgerald for technical
support and data compilation.
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